Must vs. have to
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Must vs. have to
Must和have to都表达了义务和必须，但是有小区别:
• Must表达了讲话人的主观感受，而have to表达的是一种非个人因素的意见:
• Must表达了讲话人的主观感受，而have to表达的是一种非个人因素的意见:
You must come.你必须来。(我要求你来。)
You have to come.你必须来。(规定了你要来。)
You have to come.你必须来。(规定了你要来。)
Must I wear this tie?我必须戴这条领带吗？(你怎么看的？)
Do I have to wear this tie?我必须戴这条领带吗？(有关于领带的规定？)
Do I have to wear this tie?我必须戴这条领带吗？(有关于领带的规定？)
• Have to 主要表达了通常的义务，而must表达了特殊的义务:
I have to brush my teeth twice a day. 我每天必须刷两次牙。
I must tell you something. 我必须告诉你一些事。
重要: 要表达义务、责任或必须，在将来时或过去时中，我们不使用must和need，而用have to代替:
We must (need to) buy another ticket.我们必须买另外一张票。
We had to buy another ticket yesterday. 我们昨天应该买另外一张票。
We'll have to buy another ticket later. 我们等会儿应该再买一张票。
We had to buy another ticket yesterday. 我们昨天应该买另外一张票。
We'll have to buy another ticket later. 我们等会儿应该再买一张票。
否定形式mustn't和don't have to含义完全不同:
• Mustn't表达的是禁止:
• Mustn't表达的是禁止:
You mustn't drive. 你不能开车。
• Don't have to 表达了没有义务或者必须性:
You don't have to drive. 你不必开车。
练习 1
Last week, we go on a class trip to the local prison. Our teacher said he wanted to show us what happen to us if we didn't learn our multiplication tables. When we arrived, the prisoners were having an algebra class. My friend Pete asked them if they were in prison because they didn't know their multiplication tables, and they all said 'No'. They said they were in jail because the judges didn't know how to count. 'I stole two cars and got twelve years in prison,' said one. 'And that just doesn't add up. If you really want to stay out of prison, forget mathematics. You study law!'
Last week, we had to 1 go on a class trip to the local prison. Our teacher said he wanted to show us what would 2 happen to us if we didn't learn our multiplication tables. When we arrived, the prisoners were having an algebra class. My friend Pete asked them if they were in prison because they didn't know their multiplication tables, and they all said 'No'. They said they were in jail because the judges didn't know how to count. 'I stole two cars and got twelve years in prison,' said one. 'And that just doesn't add up. If you really want to stay out of prison, forget mathematics. You ought to 3 study law!'
1 had to: This is the best choice here. Because the narrator is speaking about an obligation in the past (the necessity of going on the class trip), we use 'had to' to correctly complete the construction.
1 ought to: Because the narrator is speaking about a past event (last week), we cannot use 'ought to', which is a present tense auxiliary and expresses a sense of a strong suggestion, and is usually used in reference to the future.
1 must: Because the narrator is speaking about a past event (last week), we cannot use 'must', which is a present tense auxiliary and which expresses a sense of obligation and usually refers to the future. Also, 'must to' is grammatically incorrect.
1 need to: Because the narrator is speaking about a past event (last week), we cannot use 'need to', which is a present tense auxiliary and expresses a sense of obligation and usually refers to the future.
2 would: This is the best choice here. Because the teacher is expressing a 'possibility', we use the conditional auxiliary 'would' to show what 'may or may not' happen to the children 'if' they do not learn their multiplication tables.
2 needs: 'Needs happen to us' is grammatically incorrect. The correct construction would be: 'has to happen to us'. If the teacher said this, he would be expressing that if the children don't learn their multiplication, they deserve to be in prison.
2 ought: 'Ought happen to us' is grammatically incorrect. The correct construction would be: 'has to happen to us'. If the teacher said this, he would be expressing that if the children don't learn their multiplication, they deserve to be in prison.
2 has: 'Has happen to us' is grammatically incorrect. The correct construction would be: 'has to happen to us'. If the teacher said this, he would be expressing that if the children don't learn their multiplication, they deserve to be in prison.
3 ought to: This is the best choice here. The prisoner is giving the children advice. He says that it would be best for them to study law. 'Ought to' expresses a strong suggestion, and is generally used to give advice about the future.
3 need: 'You need study law' is grammatically incorrect. We must say: 'You need to study law'.
3 must to: 'You must to study law' is grammatically incorrect. We must say: 'You must study law', although this is an uncommon construction which emphasizes obligation rather than suggestion.
3 should to: 'You should to study law' is grammatically incorrect. We say: 'You should study law' to indicate this suggestion.
练习 2
Change the following sentences from present to past tense by replacing the auxiliary 'must' with a different verb of obligation. Be careful! You may need to use more than one word!
Philip learn how to swim before his vacation to Bali.
Everyone at the office attend the staff meeting.
Philip learn how to swim before his vacation to Bali.
Everyone at the office attend the staff meeting.
Change the following sentences from present to past tense by replacing the auxiliary 'must' with a different verb of obligation. Be careful! You may need to use more than one word!
Philip [not done] had to 1 learn how to swim before his vacation to Bali.
Everyone at the office [not done] had to 2 attend the staff meeting.
Philip [not done] had to 1 learn how to swim before his vacation to Bali.
Everyone at the office [not done] had to 2 attend the staff meeting.
1 had to: When expressing necessity in the past, we cannot use 'must'. We replace 'must' with a conjugated form of 'have to' or 'need', both of which can express necessity or obligation in the past. Examples: 'I needed to make a phone call before leaving' or 'I had to run some errands before meeting Francine at the baseball game'.
2 had to: When expressing necessity in the past, we cannot use 'must'. We replace 'must' with a conjugated form of 'have to' or 'need', both of which can express necessity or obligation in the past. Examples: 'I needed to see her one last time before dying' or 'I had to get in shape before running the marathon'.
练习 3
Metalhead: DarkBreath be the greatest metal guitarist alive today.
Edward: I heard that after he was in that car accident, he practise for five hours per day for two years!
Metalhead: Yeah, but I bet he doesn’t practise any more now!
Edward: I wish my name were DarkBreath.
Edward: I heard that after he was in that car accident, he practise for five hours per day for two years!
Metalhead: Yeah, but I bet he doesn’t practise any more now!
Edward: I wish my name were DarkBreath.
Metalhead: DarkBreath must 1 be the greatest metal guitarist alive today.
Edward: I heard that after he was in that car accident, he had to 2 practise for five hours per day for two years!
Metalhead: Yeah, but I bet he doesn’t need to 3 practise any more now!
Edward: I wish my name were DarkBreath.
Edward: I heard that after he was in that car accident, he had to 2 practise for five hours per day for two years!
Metalhead: Yeah, but I bet he doesn’t need to 3 practise any more now!
Edward: I wish my name were DarkBreath.
1 must: The only grammatically correct choice here is "must (be)". In this kind of context, it expresses an evaluation or conclusion (here, the Metalhead's evaluation of different guitar players' abilities). A similar example: "Daniel's jacket is stained with the victim's blood! He must be the murderer!".
1 had to: The Metalhead's statement is about the present, as indicated by the word "today" (meaning "in the present day", or "at this time"). Therefore, there is no good reason to use the past-tense verb "had to" here.
1 needs: This choice is grammatically incorrect. In this context, "needs" would have to be followed by a full infinitive verb, including the word "to". For example: "Bruno needs to be careful when trekking through the jungle".
2 had to: Edward is referring to a period of time in the past: the two years following "that car accident" (a car accident which happened in the past). "Had to" is used instead of "must" or "needs to" in the past tense. Another example: "The doctor told me that I had to give up sugar".
2 must: We cannot use the verb "must" in the past tense.
2 needs to: "Needs to" is a present-tense verb, but this sentence is referring to the past.
3 need to: DarkBreath doesn't need to practise any more: this sentence implies that it is no longer necessary for Darkbreath to practise guitar, because he is so skilled. A similar example: "I don't need to sleep any more. I am a cyborg now".
3 had to: This option is grammatically incorrect for two reasons. Firstly, the sentence is about the present, as indicated by the term "any more" (which refers to something which is no longer the case now). Secondly, negation in the past tense is formed using didn't (or did not) followed by the infinitive of the verb (without "to"). If this sentence were about the past, we would say "He didn't have to practise".
3 must: Modal auxiliary verbs like "must" are negated in a different way than other verbs. We do not use "don't" or "do not" with verbs like must, can, may, might: rather, we simply use "not" after the verb. For example: "You must not arrive late"; "He can't swim".
练习 4
Jean: Icarus, you come to watch the new Julie Del Fi film with me tonight. You will love it.
Icarus: Thank you for the invitation, Jean, but I’m too tired! I stay up late last night in order to see the lunar eclipse.
Jean: What was it like?
Icarus: Unbelievable. I pinch myself to make sure I wasn’t dreaming.
Icarus: Thank you for the invitation, Jean, but I’m too tired! I stay up late last night in order to see the lunar eclipse.
Jean: What was it like?
Icarus: Unbelievable. I pinch myself to make sure I wasn’t dreaming.
Jean: Icarus, you must 1 come to watch the new Julie Del Fi film with me tonight. You will love it.
Icarus: Thank you for the invitation, Jean, but I’m too tired! I had to 2 stay up late last night in order to see the lunar eclipse.
Jean: What was it like?
Icarus: Unbelievable. I had to 3 pinch myself to make sure I wasn’t dreaming.
Icarus: Thank you for the invitation, Jean, but I’m too tired! I had to 2 stay up late last night in order to see the lunar eclipse.
Jean: What was it like?
Icarus: Unbelievable. I had to 3 pinch myself to make sure I wasn’t dreaming.
1 must: "Must" generally expresses obligation in the present tense. In this sentence, Jean is (correctly!) using it to make a strong suggestion: Icarus is not actually obliged to watch the movie, but Jean is urging him to do so because he thinks that Icarus will love it. Another example: "It's been great to meet you! You must come over to our house for a glass of wine sometime!".
1 had to: "You had to" expresses obligation in the past. This doesn't make sense in a sentence which contains the word "tonight"!
1 need: This choice is grammatically incorrect. In this context, "you need" would have to be followed by a full infinitive verb, including the word "to". For example: "I need to obtain some sharper knives".
2 had to: To refer to an obligation or necessity in the past, we use "had to" instead of "must" or "need to". Because Icarus wanted to see the lunar eclipse, it was necessary for him to stay up late. Another example: "I had to learn to speak Vietnamese fluently before I could even apply for this job".
2 need to: "I need to" is a present-tense verb, but this sentence is referring to the past. We can tell this because Icarus refers to "last night".
2 must: This sentence is about the past, as we can tell from Icarus's reference to "last night". The verb "must" cannot refer to the past.
3 had to: Icarus uses "I had to" again here for the same reason as before. It was necessary for him to pinch himself in order to determine that he was not dreaming. "To pinch oneself" is a common expression which refers to squeezing one's skin in order to feel a small amount of pain (and therefore know that one is awake).
3 need to: Icarus is still talking about the events of "last night", so he cannot use the present-tense verb "I need to" here.
3 must: Icarus is still talking about the events of "last night", so he cannot use the present-tense verb "I must" here.
练习 5
For each sentence, select a way of expressing something similar.
You should learn how to cook. → You learn how to cook.
You will certainly find a partner if you do. → You find a partner if you do.
Still, you must be patient when looking for love. → Still, you be patient when looking for love.
You should learn how to cook. → You learn how to cook.
You will certainly find a partner if you do. → You find a partner if you do.
Still, you must be patient when looking for love. → Still, you be patient when looking for love.
For each sentence, select a way of expressing something similar.
You should learn how to cook. → You ought to 1 learn how to cook.
You will certainly find a partner if you do. → You are sure to 2 find a partner if you do.
Still, you must be patient when looking for love. → Still, you have to 3 be patient when looking for love.
You should learn how to cook. → You ought to 1 learn how to cook.
You will certainly find a partner if you do. → You are sure to 2 find a partner if you do.
Still, you must be patient when looking for love. → Still, you have to 3 be patient when looking for love.
1 ought to: "You should" and "you ought to" have the same meaning. Both phrases express a recommendation or suggestion for a future action. Another example: "He ought to spend more time outside" or "He should spend more time outside".
1 are sure to: "You are sure to learn" does not have the same meaning as "You should learn". "You are sure to learn" means "You will certainly learn", and expresses a probable future action. Another example: "He is sure to become famous if he keeps writing such great songs".
1 have to: "You have to learn" does not have the same meaning as "You should learn". "You have to learn" is closer in meaning to "you must learn", and expresses an obligation or necessity, rather than a suggestion. For example: "We cannot afford to eat out so often. We have to learn how to cook, otherwise we will run out of money".
2 are sure to: "You are sure to find a partner" has a similar meaning to "You will certainly find a partner". Both express a probable result or outcome. Another example: "We are sure to win this match. The opposition have barely won any of their matches".
2 ought to: "You ought to find" does not have a similar meaning to "You will certainly find". "You ought to find" means "You should find", and expresses a recommendation for a future action. For example: "You ought to have a weekly budget".
2 have to: "You have to find" does not have a similar meaning to "You will certainly find". "You have to find" means "You must find", and expresses an obligation or necessity. For example: "You have to lift the handle in order to lock the door".
3 have to: "You must be patient" is closest in meaning to "you have to be patient" out of the three options here. Both express this it is necessary to be patient in order to find love. Note that "must" may imply that this is the speaker's opinion, while "have to" suggests that it is simply the truth.
3 are sure to: "You are sure to be patient" is not similar in meaning to "You must be patient". "You are sure to be patient" means "You will certainly or probably be patient", which doesn't make sense in this context. An example: "We are sure to arrive before nightfall" (We will certainly arrive before nightfall).
3 ought to: "You ought to be patient" is somewhat different in meaning to "You must be patient". "You must" and "you have to" express an obligation or necessity, whereas "you ought to" and "you should" express a recommendation or suggestion.
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