2.  This modal auxiliary indicates opportunities we have in order to complete something.  I can go to the gym on weekends.  S Aux VSF  The auxiliary “can” is for all persons.  You can talk about happiness or sadness.  He can travel tomorrow.  They can study in the morning.  The verb in all cases is always in simple form (do not modify it)

3.  I can not go with you because I have a lot of work.  I can’t go with you …  To form the negative we use can + not or the contraction can’t.  He can’t go out tonight.  They can’t play outside because they’re sick.  You can’t smoke in here.

4.  It is necessary to invert the subject and the auxiliary.  Can you watch TV at night?  Yes, I can.  No, I can’t.  Can he finish the report next week?  Yes, he can.  No, he can’t.  Can they buy the tickets for me?  Yes, they can.  No, they can’t.  What can I do?  What can you do?

5.  This modal auxiliary expresses what is a good idea to do.  I should eat vegetables.  S aux VSF  The auxiliary “should” is for all persons.  You should study for the exam.  She should do exercise.  They should drink water every day.

6.  To form the negative we use should + not.  I should not smoke.  You can also use the contraction shouldn’t.  I shouldn’t smoke.  You shouldn’t drink a lot.  He shouldn’t watch too much TV.  They shouldn’t drink and drive.  We shouldn’t waste water.

7.  It is necessary to invert the subject and the auxiliary.  Should I eat red meat every day?  Yes, you should.  No, you shouldn’t.  Should you go to the party?  Yes, I should.  No, I shouldn’t.  Should she practice more?  Yes, she should.  No, she shouldn’t.  What should I do?  What should you do?

8.  This expression indicates obligation or necessity.  I have to clean my room on Saturdays.  S have to VSF  Have to is for I, You, We, and They.  For he, she, and it, we use “has to”.  He has to do the homework every day.  She has to work hard to buy a house.

9.  To form the negative, it is necessary to use an auxiliary. The auxiliaries are don’t and doesn’t.  I don’t have to finish today.  You don’t have to show all the presentations.  They don’t have to return tomorrow.  We don’t have to clean all the room.  For he, she, and it.  He doesn’t have to work at home.  She doesn’t have to cook every day.

10.  We begin with do or does.  Do you have to work every day?  Yes, I do.  No, I don’t.  Does he have to travel frequently?  Yes, he does.  No, he doesn’t.  Does she have to wear a uniform?  Yes, she does.  No, she doesn’t.  What do you have to do every day?  What does he have to do on weekends?