The present simple tense: irregular verbs (affirmative form): How and When to Use in English

He does his best. When the subject is he/she/it, for verbs ending in -o like to do, we form the present simple tense by adding -es (to do → does). Examples: he does his English homework; she goes to work.

You can say, for example, I do my best with the subject I, but you need to add -es at the end of the verb when the subject is he/she/it.

They wash their clothes. With all plural subjects including they, the present simple form is the same as the infinitive form without to (to wash → wash). Example: they wash their car.

When the subject is he/she/it (or the name of a person, object etc.), you add -es after the infinitive form of all verbs ending in -sh. However, we do not do it here, because the subject is they. Example: he washes his car.

The baby cries all night long. For verbs that end in a consonant (here r) + y like to cry, you form the present simple tense after he/she/it by removing the y and adding -ies. Example: he tries to arrive on time (to try → tries). 

You could say you cry all night long because the present simple form for all subjects, except for he/she/it, is the same as the infinitive form without to (to cry), but here the subject is the baby (=he/she).

Betty replies to an email. In the present simple tense and when the subject is he/she/it (Betty=she), for all verbs ending in a consonant + -y (like reply) remove the -y and add -ies at the end. Example: the bird flies in the sky.

My father goes to his dance class. For verbs ending in -o like to go, form the present simple tense with subjects like he/she/it (my father=he) by adding -es. Example: it goes well.

Caroline brushes her teeth. To brush ends in -sh so you need to add -es to form the present simple tense after subjects like he/she/it. Example: she refreshes the page.

She teaches English. With subjects like he/she/it and if a verb ends in -ch, you need to add -es at the end of the verb (to teach → teaches) to obtain the present simple tense. Example: my son (=he) watches TV.

Roger relaxes during his vacation. When a verb ends in -x in its infinitive form, add -es (to relax → relaxes) to form the present simple tense after subjects like he/she/it (Roger=he). Example: she fixes my computer.

You try new food. With the subject you, simply use the infinitive form without to (to try) to form the present simple tense. Example: you speak English very well.