Auxiliary, or helping verbs, are used before infinitives to add a different meaning. For example, you use auxiliary verbs to say:
That someone is able to do something,
That someone is allowed to do something, or
That someone has to do something.
The helping verbs are can, could, would, should, ought to, will, shall, may, might and must.
Can and could
Use can and could to say that someone is able to do something.
— She can draw really good pictures.
— Philip can run faster than Matt.
— Can you ride a bike?
— Can you help me with my homework?
— She could already read before she started school.
— Our teacher said we could go home early.
— I ran as fast as I could.
— Sarah could not come to the party because she was ill.
Note and remember
Could is the simple past tense form of can. (Read more about the simple past)
When you put not after can, write it as one word: cannot. Example:
— They cannot find their way home.
The contraction of cannot is can’t (Read more about Contractions), and the contraction of could not is couldn’t.
— They can’t find their way home. I’m full. I can’t eat anymore.
— Sarah couldn’t come to the party because she was ill.
You may also use can and could to say that someone is allowed to do something.
— My mom says you can come to our house for dinner.
— Dad says I can’t walk to school on my own.
— You can’t go in there without a ticket.
— Mom said I could have ice cream after my dinner.
— The big sign on the gate said PRIVATE, so we couldn’t go in.
Can and could are also used for asking for information or help, for offering something, and for suggesting something. (Read more about how to make suggestions)
— Can you tell me if this train goes to Topeka?
— Could you show me where the accident happened? Could you open that window, please?
— You can borrow my pen, if you like.
— Your sister could come with us, if she wanted to.
— I could lend you my football.
— We can go to the library instead.
— You could ask your dad to help us.
— John can borrow his brother’s skates.
Will and would
Use will and would when you are asking someone to do something.
— Will you please stop making that noise?
— Would you pass me that book, please?
— Please, will you close the door?
You can also use will and would to offer something or to suggest something.
— Will I hold this end of the rope?
— Will I carry the bag for you?
— Would you like another drink?
— Which cake would you like?
Note and remember
The contraction of will not is won’t and the contraction of would not is wouldn’t:
— Won’t you stay and eat with us?
— Wouldn’t it be better to wait?
Shall and should
You can use shall and should to ask for advice, offer something and suggest something.
— Should I bring waterproof clothes?
— Should I phone the police?
— Shall we go home now?
— Shall I go by car, or will it be better to walk?
— Shall I help you with that heavy bag?
— You should try that new French restaurant.
You use ought to to make strong suggestions and talk about someone’s duty.
— You look tired. You ought to go to bed early tonight.
— I ought to get more physical exercise.
— We ought to lock the door when we leave home.
— You ought to turn off the computer when you’re not using it.
— You ought to know how to spell your own name.
— The teacher ought to make his classes more interesting.
Use must to talk about things that you have to do.
— I must mail this letter today.
— You must speak louder. I can’t hear you.
— Children must not play with matches.
— Go to bed now. Oh, must I?
— Why must I do my homework tonight?
Note and remember
Must keeps the same form in the past tense.
The contraction of must not is mustn’t.
— She mustn’t let the dog sleep on her bed.
May and might
Use may to ask if you are allowed to do something and to tell someone that they are allowed to do something.
— “May I go out to play now?” “Yes, you may.”
— May I borrow your pen?
— Please, may I see your ticket?
— John may leave now, but Sally may not.
— May Kenny come with us to the movies?
Use may and might to talk about things that are possible or likely.
Take an umbrella. It might rain.
I may not have time to go swimming tonight.
We might go to the party later.
If you’re not careful, you may hurt yourself.
“Are you going to the concert?” “I don’t know. I might or I might not.”
Complete the sentences below by writing can or can’t on the blanks.
1. You………………….borrow my book, if you want to.
2. Sam looked everywhere but he………………….find his pencil.
3. Don’t help me. I………………….do it by myself.
4. Sandy………………….open the window. She’s not tall enough to reach it.
5. “Why………………….John come out to play?” “Because he’s ill.”
6. This is a film for adults only. Children………………….watch it.
7. …………………. you help me with this heavy bag?
8. They’ve lost the map and………………….find their way back to the hotel.
Tell whether each sentence below uses may or may not correctly.
1. Andrew may not go out to play now because he has finished his homework.
2. Take an umbrella. It may not rain.
3. Please, may we not watch television now?
4. You may not hurt yourself with that sharp knife.
5. I may come out to play later if I’m feeling better.
6. They are late. The bus may not have broken down.
7. “May I read the story you have written?” “Yes, you may not.”
8. “May Andrew stay for dinner?” “Yes, he may.”