1. They / to do a science project this year 2. We / shout in class 3. I / forget my mobile phone 4. I / work on Saturdays 5. You / drink this water. It will make you ill 6. I / learn all these words for tomorrow's lesson 7. She / finish this report by tomorrow

1.  don't have to

2.  mustn't

3. don't have to

4. don't have to

5. mustn't

6. don't have to

7. doesn't have to

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We recommend you the best model  of new mountain bike.It has fifteen speeds and it is suitable for world champion.The speeds are first-class.It is really comfortable.The breaks work fine.The bike is good on the turns.It is great overcomes bumps.It is easy goes to the mountain.
You can roll out the bike,get it and test it in the street.You will love this bike and don't agree to exchange it for another model.You can feel yourself like an ass for those who are on conventional bike will difficult to keep up with you.They will ask you to wait.

1.Summer time was first introduced in England in 1908. Hours transferred to one hour ahead. 2.Kangaroo associated with Australia. 3.Keith - mammal, but he lives in the sea. 4. The elephant lives in India and in Central Africa. 5.In many countries, there is an animal of the monument to the dog, in India - a monument to the elephant in the United States - a monument to the monkey. 6.When and by whom was invented by phone? 7.Bike - the perfect vehicle. 8.The guiter appeared in Spain in the 13th century. 9.No one knows when man invented the wheel. 10.The subject and predicate - the principal terms of the proposal. 11. Detective roman - one of the literary genres. 12. A detective novel helps pass the time while travelling.