Could
理解语法是理解一门语言的关键。
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Could
Could有很多用法:
• can的过去式:
• can的过去式:
When I was younger, I could walk for miles. 当我年轻点的时候，我能行走数英里。
• 条件式现在时:
I could stay with her all my life. 我会与她终生相伴。
He could be here with us if he weren't abroad all the time. 要不是他长期在国外，他本可以现在与我们一起。
• 可能性:与can类似, 但是could侧重怀疑:
He could be right. 他可能是对的。
• 礼貌:
Could I have some change please? 能给我换点零钱吗？
Could you pass me the bread please? 能递给我面包吗？
练习 1
Philip: you see the suit Bruno was wearing yesterday? It was beautiful. Really suited his shoulders.
Kevin: I didn't see Bruno yesterday. I was watching the rugby. You like sports, you?
Philip: I like squash and wrestling. Basically I am a fan of any sport with balls or close physical contact.
Kevin: you? I tell.
Kevin: I didn't see Bruno yesterday. I was watching the rugby. You like sports, you?
Philip: I like squash and wrestling. Basically I am a fan of any sport with balls or close physical contact.
Kevin: you? I tell.
Philip: Did 1 you see the suit Bruno was wearing yesterday? It was beautiful. Really suited his shoulders.
Kevin: I didn't see Bruno yesterday. I was watching the rugby. You like sports, don't 2 you?
Philip: I like squash and wrestling. Basically I am a fan of any sport with balls or close physical contact.
Kevin: Are 3 you? I couldn't 4 tell.
Kevin: I didn't see Bruno yesterday. I was watching the rugby. You like sports, don't 2 you?
Philip: I like squash and wrestling. Basically I am a fan of any sport with balls or close physical contact.
Kevin: Are 3 you? I couldn't 4 tell.
1 Did: Because Philip is asking about 'yesterday', we use the past tense auxiliary 'did' to form the interrogative construction in the past tense.
1 Have: 'Have' does not agree with the past tense construction of the sentence. However, we might say 'have you seen the suit Bruno is wearing today?'.
1 Can: 'Can' does not agree with the past tense (preterit) construction of the sentence. The present tense auxiliary 'can' is generally used to ask questions about capacity (Can you tell me how to get to the market?) or permission (Can you help me with this report?).
1 Does: 'Does' is the correct verb, but does not agree with the past tense (preterit) construction of the sentence. Also, 'does' cannot be used with the second person subject 'you'. However, we might say 'Does he cook and clean?'.
2 don't: We must use the negative form of the auxiliary to express surprise in this type of construction. 'Don't you' asks a question which supposes a positive reply. Because the sentence is in the affirmative voice, we use the negative auxiliary 'don't' to properly complete the interrogative construction.
2 do: Because the construction of the phrase is affirmative, we cannot use the affirmative auxiliary 'do' to construct a response. To express surprise, we use the negative form of the auxiliary.
2 can: 'Can' is used either to ask permission, or to ask if someone is able to do something. It does not make sense to use it here.
2 will: The future auxiliary 'will' has no place in this construction. Using it here is grammatically incorrect.
3 Are: We use the affirmative construction 'are you' to formulate the question. This question is the reply to Philip's previous statement 'I am a fan of any sport...'. Because Philip uses the verb 'to be' in his statement, Kevin's reply uses the same verb to respond.
3 Aren't: There is no need to use the negative form of the auxiliary verb here. We use the negative auxiliary 'don't' when asking questions which suppose a positive reply. Example: You have a dog, don't you?
3 Is: 'Is' is grammatically incorrect. We must use a form of the auxiliary 'to be', however the subject 'you' requires the second person form of the verb (are).
3 Will: As an auxiliary, 'will' is used to ask someone to do something or to express the future tense. It has no place in this construction.
4 couldn't: 'I couldn't tell' is the correct way to form this sentence. Here it expresses Kevin's (ironic) incapacity to see that Philip appreciates certain sports. 'I couldn't tell' expresses that Kevin is already aware of Philip's affection for certain sports.
4 wouldn't: The auxiliary 'would' (and 'wouldn't') expresses a willingness or desire. It does not make sense here as this construction requires the term 'couldn't', which express 'incapacity'.
4 shouldn't: The auxiliary 'should' (and 'shouldn't') expresses this idea of obligation or near-necessity. It does not make sense here as this construction requires the term 'couldn't', which express 'incapacity'.
4 can't: 'Can't' is the contracted form of 'cannot'. Although using it here is not grammatically incorrect, it doesn't express the past tense sense of Kevin's statement.
练习 2
Use the following words to fill in the blanks in the text. Be careful! Words may be used more than once:
should | would | could
Horatio not be drinking so much whiskey before work.
Every Tuesday, Bruno clips his toenails, even though he like to do it more often than that.
Susie thought Kevin like a new wallet for his birthday.
When he was just a boy, Bruno not distinguish between a rose and a tulip.
Kevin is out driving in his Porsche, but really he be in his office.
Icarus has been feeling really sick. He probably go to the doctor.
should | would | could
Horatio not be drinking so much whiskey before work.
Every Tuesday, Bruno clips his toenails, even though he like to do it more often than that.
Susie thought Kevin like a new wallet for his birthday.
When he was just a boy, Bruno not distinguish between a rose and a tulip.
Kevin is out driving in his Porsche, but really he be in his office.
Icarus has been feeling really sick. He probably go to the doctor.
Use the following words to fill in the blanks in the text. Be careful! Words may be used more than once:
should | would | could
Horatio should 1 not be drinking so much whiskey before work.
Every Tuesday, Bruno clips his toenails, even though he would 2 like to do it more often than that.
Susie thought Kevin would 3 like a new wallet for his birthday.
When he was just a boy, Bruno could 4 not distinguish between a rose and a tulip.
Kevin is out driving in his Porsche, but really he should 5 be in his office.
Icarus has been feeling really sick. He should 6 probably go to the doctor.
should | would | could
Horatio should 1 not be drinking so much whiskey before work.
Every Tuesday, Bruno clips his toenails, even though he would 2 like to do it more often than that.
Susie thought Kevin would 3 like a new wallet for his birthday.
When he was just a boy, Bruno could 4 not distinguish between a rose and a tulip.
Kevin is out driving in his Porsche, but really he should 5 be in his office.
Icarus has been feeling really sick. He should 6 probably go to the doctor.
1 should: 'Should' expresses the notion of duty or obligation. Neither of the other choices (would or could) fits in this sentence.
2 would: 'Would' expresses the idea of willingness or wish. We use it to form the conditional tense.
3 would: 'Would' expresses the idea of willingness or wish. We use it to form the conditional tense.
4 could: 'Could' is the past tense form of the verb 'to be able to'.
5 should: 'Should' expresses the notion of duty or obligation: Kevin is supposed to be in his office (not driving his Porsche). Neither of the other choices (would or could) fits in this sentence.
6 should: 'Should' expresses the notion of duty or obligation. Neither of the other choices (would or could) fits in this sentence.
练习 3
When he was a child, Horatio was a very curious boy. Sometimes he walk off into the jungle by himself. His family spent hours trying to find him. He have been dead for all they knew! But then the young boy returned home, after having killed a jaguar. "You go into the jungle alone", his mother say.
When he was a child, Horatio was a very curious boy. Sometimes he would 1 walk off into the jungle by himself. His family spent hours trying to find him. He could 2 have been dead for all they knew! But then the young boy returned home, after having killed a jaguar. "You shouldn't 3 go into the jungle alone", his mother would 4 say.
1 would: This is the best choice here. We often use 'would' to express habitual past action. 'He would wander off' is synonymous with 'He wandered off' or 'He used to wander off', but using 'would' makes the habitual action more clear. Example: When I was young I would play football every day.
1 could: Although it is grammatically correct, 'could' does not make sense in this construction. Using 'could' here refers to Horatio's ability or capacity to 'walk around', while this sentence describes a habitual past action.
1 should: Although it is grammatically correct, 'should' does not make sense here. 'Should' is generally used to express suggestion or obligation.
1 can: Because we are speaking about the past, 'can' is grammatically incorrect.
2 could: This is the best choice here. We use 'could' to express the possibility (conditional) that young Horatio is dead. Example: She could have been hurt in the accident, but she survived without any injuries.
2 would: 'Would' is incorrect here. 'He would have been dead' is a conditional statement that requires a second determining clause. For example: 'He would have been dead, if his family had not saved him'.
2 should: 'He should have been dead' indicates that Horatio's family wants him to be dead, and this does not make sense in the context.
2 can: Because we are speaking about the past, 'can' is grammatically incorrect.
3 shouldn't: This is the best choice here. Horatio's mother is telling Horatio not to travel alone. 'Shouldn't' best expresses a suggestion against doing something. Example: You shouldn't go in the forest on your own, Goldilocks.
3 wouldn't: Although 'wouldn't' is grammatically correct, it is incomplete. For the construction to make sense, we would say: 'You wouldn't go into the jungle alone, would you?'.
3 couldn't: Although 'couldn't' is grammatically correct, it does not make sense here. It is obvious that Horatio has gone into the jungle alone, so it doesn't make sense to say that he 'cannot' do it.
4 would: This is the best choice here. We often use 'would' to express habitual past action. 'She would say' is synonymous with 'She said' or 'She used to say', but using 'would' makes the habitual action more clear. In this way, we feel that Horatio's mother had to warn him many times. Example: My father would always tell us not to damage his flowers.
4 should: Although it is grammatically correct, 'should' does not make sense here. 'Should' is usually used to express suggestion.
4 could: Although it is grammatically correct, 'could' does not make much sense here. Because we are talking about habitual past action, it doesn't make sense to say that Horatio's mother 'could' do something, which expresses a conditional, future action.
4 can: Because we are speaking about the past, 'can' is grammatically incorrect.
练习 4
Kevin: I would be more sympathetic if I , but she deserves the punishment she gets.
Susie: You're disgusting. She's only six years old!
Kevin: But she stole my wallet! I wish you take my side just once.
Susie: Sorry, Kevin. You're right. I think six-year-old girls should be arrested.
Susie: You're disgusting. She's only six years old!
Kevin: But she stole my wallet! I wish you take my side just once.
Susie: Sorry, Kevin. You're right. I think six-year-old girls should be arrested.
Kevin: I would be more sympathetic if I could 1, but she deserves the punishment she gets.
Susie: You're disgusting. She's only six years old!
Kevin: But she stole my wallet! I wish you would 2 take my side just once.
Susie: Sorry, Kevin. You're right. I think six-year-old girls should be arrested.
Susie: You're disgusting. She's only six years old!
Kevin: But she stole my wallet! I wish you would 2 take my side just once.
Susie: Sorry, Kevin. You're right. I think six-year-old girls should be arrested.
1 could: 'Could' completes the conditional statement introduced by 'would' in the first clause. This sentence indicates that Kevin would be more sympathetic if he were 'capable' or 'willing' to be.
1 would: 'Would' is used to express conditional thoughts and actions, but it cannot indicate Kevin's capacity to be sympathetic, which is necessary in this construction.
1 should: We use 'should' to express a strong suggestion. It is not appropriate in this construction.
1 am: 'Am', the present tense from of the verb 'to be', does not belong in this construction. We want to express Kevin's capacity to be sympathetic, which we cannot do with 'am'.
2 would: 'Would' correctly expresses Kevin's strong desire for Susie to agree with him. Because this is a conditional wish, which is not a certainty, we use 'would' to express it. 'I wish you would' is a very common beginning for conditional constructions.
2 should: 'Should' is used to express a strong suggestion. It is inappropriate in this construction, as we cannot write or say 'I wish you should'. The phrase 'I wish' already carries the conditional sense of the construction. Kevin might say 'You should take my side', however.
2 will: We cannot use 'will' here because it is an auxiliary used to express a future tense. Kevin is using a conditional construction which doesn't use the future tense.
练习 5
Bob: Hey Soph, you change the channel on the TV for me? I lost the remote and I don't feel like getting up.
Sophie: Robert William Carter! you really be that lazy?
Bob: Oh, come on. I had a long day at work today. I'm exhausted.
Sophie: Fine, fine. But I doubt that your day have been as awful as mine.
Bob: I had a fight with one of the test monkeys!
Sophie: Well, I to perform heart surgery on a 90-year-old woman in the dark because the hospital lost power!
Bob: You win. I'll change the channel.
Sophie: Robert William Carter! you really be that lazy?
Bob: Oh, come on. I had a long day at work today. I'm exhausted.
Sophie: Fine, fine. But I doubt that your day have been as awful as mine.
Bob: I had a fight with one of the test monkeys!
Sophie: Well, I to perform heart surgery on a 90-year-old woman in the dark because the hospital lost power!
Bob: You win. I'll change the channel.
Bob: Hey Soph, can 1 you change the channel on the TV for me? I lost the remote and I don't feel like getting up.
Sophie: Robert William Carter! Can 2 you really be that lazy?
Bob: Oh, come on. I had a long day at work today. I'm exhausted.
Sophie: Fine, fine. But I doubt that your day could 3 have been as awful as mine.
Bob: I had a fight with one of the test monkeys!
Sophie: Well, I had 4 to perform heart surgery on a 90-year-old woman in the dark because the hospital lost power!
Bob: You win. I'll change the channel.
Sophie: Robert William Carter! Can 2 you really be that lazy?
Bob: Oh, come on. I had a long day at work today. I'm exhausted.
Sophie: Fine, fine. But I doubt that your day could 3 have been as awful as mine.
Bob: I had a fight with one of the test monkeys!
Sophie: Well, I had 4 to perform heart surgery on a 90-year-old woman in the dark because the hospital lost power!
Bob: You win. I'll change the channel.
1 can: This is the best choice here. Bob is simply asking Sophie to change the channel. 'Can' is often used in informal speech to ask if someone 'would please' do something.
1 may: Although it is not grammatically incorrect, 'may' is not appropriate here. The action of 'changing the channel on the TV' is quite informal. 'May' is usually found in more formal dialogues (professional telephone conversations, for example).
1 do: Although it is not grammatically incorrect, 'do' does not make sense here. 'Do you change the channel on the TV for me?' asks if Sophie performs the action of changing the channel, in a very strange way.
1 make: 'Make' is grammatically incorrect here. We could say, however: 'I'll make you change the channel', but this is quite silly.
2 Can: This is the best choice here. Sophie is asking Bob if he is so lazy that he cannot even get up to change the channel on the TV. 'Can you really be that lazy?' is an exaggerated form of the more simple question: 'Are you really that lazy?' We use 'can' in this case to emphasize the disbelief.
2 Can't: We cannot use the negative construction 'Can't' to ask this question, we must use an affirmative construction instead.
2 Are: 'Are' is grammatically incorrect. We cannot use the auxiliary 'be' when the sentence already uses another form of 'be'.
2 Aren't: 'Aren't' is grammatically incorrect. We cannot use the auxiliary 'be' when the sentence already uses another form of 'be'.
3 could: This is the best choice here. In the past tense, 'can' is replaced with 'could'. In this case, we are using the present perfect tense (have + been), and because this tense indicates a relationship with the past, we must use 'could'.
3 will be able to: 'Will be able to have been' is grammatically incorrect. We cannot combine the future tense (will be able to) with the present perfect (have been).
3 is: 'Is have been' is grammatically incorrect.
3 shall: 'Shall have been' has a similar meaning to 'will have been', which is the future perfect tense. There is no reason to refer to the future in this context. Also, note that 'shall' is mostly used to emphasize the speaker's intention, so is especially unnatural here. Example: 'I shall master the English language! I am determined to do so!'.
4 had: This is the best choice here. To express necessity or obligation in the past, we use 'had to'. Because Sophie is talking about her day at work which has already ended, we know that we must use the preterit 'had'.
4 have: Because we are talking about the past, it is doesn't make sense to use a present tense verb (have).
4 must: 'Must' cannot be used to express necessity or obligation in the past. We use 'needed' or 'had to' to express this idea in the past.
4 need: 'Need' cannot be used to express necessity in the past, unless it is conjugated in the appropriate tense (needed to).
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