16. Must, have to, need TO

HAVE TO DO - RESPONSIBILITIES

Use 'have to' in the past, present and future to express responsibility or necessity. NOTE: 'have to' is conjugated as a regular verb and therefore requires an auxiliary verb in the question form or negative.

• We have to get up early.
• She had to work hard yesterday.
• They will have to arrive early.
• Does he have to go?

MUST DO - OBLIGATIONS

Use 'must' to express something that you or a person feels is necessary. This form is used only in the present and future.

• I must finish this work before I leave.
• Must you work so hard?
• John must explain this if he wants his students to succeed.
• It's late. I must get going!

DON'T HAVE TO DO - NOT REQUIRED, BUT POSSIBLE

The negative form of 'have to' expresses the idea that something is not required. It is however, possible if so desired.

• You don't have to arrive before 8.
• They didn't have to work so hard.
• We don't have to work overtime on Saturdays.
• She didn't have to attend the presentation.

MUSTN'T DO - PROHIBITION

The negative form of 'must' expresses the idea that something is prohibited - this form is very different in meaning than the negative of 'have to'!

• She mustn't use such horrible language.
• Tom. You mustn't play with fire.
• You mustn't drive more than 25 mph in this zone.
• The children mustn't go into the street.

IMPORTANT: The past form of 'have to' and 'must' is 'had to'. 'Must' does not exist in the past.

• Did he have to leave so early?
• He had to stay overnight in Dallas.
• She had to pick the children up from school.
• Did they have to do the work over again?

NEED TO DO - IMPORTANT FOR SOMEONE

Use 'need to' to express that something is important for you to do. This form is usually used for something that is important one time, rather than referring to a responsibility or duty.

• She needs to go to Seattle next week.
• Do you need to get up early tomorrow?
• I need to spend more time with my children because I've been so busy lately.
• We need to focus on getting new business this month.

DON'T NEED TO DO - NOT NECESSARY, BUT POSSIBLE

Use the negative form of 'need to' to express that something isn't necessary, but possible. At times, English speakers use 'don't need to' to express that they don't expect someone to do something.

• You don't need to come to the meeting next week.
• She doesn't need to worry about her grades. She's a great student.
• I don't need to work next Monday!
• Peter doesn't need to worry about money because he's independently wealthy.

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16.1 Read each sentence implying OBLIGATION, then make it refer to the past (elementary).

1. You must do it at once. e.g. You had to do it at once.
2. He mustn't tell me. e.g. He wasn't to tell me.
3. She has to wash the glasses. e.g. She had to wash the glasses.
4. He is not to come before seven. e.g. He wasn't to come before seven.
5. You'll have to read it again.
6. He says I am not to be trusted.
7. They must sell it at once.
8. We shall have to leave in the morning.
9. I'm not to repeat it.
10. I shall have to come again.
11. He says you are not ot listen to them.
12. They must change their shoes.
13. He is surprised that he is not to bring one with him.
14. You are not to choose a green one.
15. We have to begin before five o'clock.
16. I must work as hard as I can.
17. We shall have to do it again.
18. He says you're not to drink it all.
19. I have to light a fire.
20. He has to go home early.
21. He mustn't read the whole book.
22. She says "I'm not to lay the table before twelve o'clock"
23. I shall have to give you a new one.
24. She mustn't go home alone.
25. They'll have to do what they're told.

16.2 Read the following sentences implying an ABSENCE OF OBLIGATION, and make them refer to the past (elementary).

1. You needn't spend it all. e.g. You didn't have to spend it all.
2. She won't have to come again. e.g. She didn't have to come again.
3. I needn't do my homework again.
4. My sister doesn't have to go to work.
5. The children won't need to get up so early.
6. They haven't got to go back alone, have they?
7. She needn't cook them all.
8. I must go at once, but you needn't.
9. They must pay twice, but we shan't have to .
10. You haven't got to answer all the questions.
11. You don't need t carry so much.
12. So I shan't have to go our after all.
13. He won't have to come on foot , will he?
14. We needn't listen to them.
15. THe students don't have to write in ink.
16. They won't have to read the whole book, will they?
17. She doesn't have to come every week.
18. I shan't have to buy another one.
19. We don't need to call him "Sir".
20. She won't have to walk the whole way, will she?