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21. Rewrite the sentences in the interrogative and negative form.
1)She has to do these exercises again/
2)We had to work hard to learn how to solve such problems.
3)He'll have to answer her letter without any delay.
4)You have to speak louder to make yourself heard.
5)They had to repeat their experiment.
6)I'll have to work from morning till night to earn my living.
7)She'll have to give a talk at the next seminar.
8)We had to change the plan for the experiment/
9)We'll have to put it off till next time.

22.Answer these questions/ Use the words suggested.
Example Why didn't you stay longer? (go home)
-I had to go hame.
1)Why didn't you come to see us? (write an essay)
2)Why didn't John ride his bicycle? (repair it)
3)Why didn't the meet us (look after? Granny)
4)Why didn't the children play football? (stay at home)
5)Why didn't Ann learn the poem? (translate the text)
6)Why didn't she come back in time? (call on her sick friend)
7)Why didn't she go to the cinema? (do a lot of work about the house)
8)Why didn't he meet his friends? (go on a business trip)

1) She doesn`t have to do these exercises again.Does she have to do these exercises again?2) We didn`t have to work hard to learn how to solve such problems.Did we have to work hard to learn how to solve such problems?3)He won`t have to answer her letter without any delay.-Will he have to answer her letter without any delay?4)You don`t have to speak louder to make yourself heard.-Do you have to speak louder to make yourself heard?5)They didn`t have to repeat their experiment.-Did they have to repeat their experiment?6)I won`t have to work from morning till night to earn my living.- Will you(I) have to work from morning till night to earn my living?7)She won`t have to give a talk at the next seminar.- Will she have to give a talk at the next seminar?8)We didn`t have to change the plan for the experiment-Did we have to change the plan for the experiment?9)We won`t have to put it off till next time.-Will we have to put it off till next ti me?1) I had to write an essay.2) He had to repair it.3) I had to look after Granny.4) They had to stay at home.5) Ann had to translate the text.6) She had to call on her sick friend.7) She had to do a lot of work about the house.8) He had to go on a business trip.