Exercise 1

2. c

3. b

4. h

5. f

6. a

7. e

8. g

Exercise 2

2. we (please) review Unit 6? OR we review Unit 6, please?

3. I (please) borrow your pen? OR I borrow your pen, please?

4. I look at your (class) notes?

5. I come late to the next class?

6. my roommate (please) come to the next class with me? OR my roommate come to the next class with me, please?

7. I (please) ask a question? OR I ask a question, please?

8. we (please) use a dictionary? OR we use a dictionary, please?

9. we (please) leave five minutes early? OR we leave five minutes early, please?

10. my sister goes on the class trip with the rest of the class?  

Exercise 3  

2. can bring

3. can bring

4. can't OR cannot drink

5. can pay

6. can pay

7. may not pay

8. may not purchase

9. can't OR cannot get

10. may swim

 Exercise 4

taking --> take

mayn't --> can't

comes --> come

could --> can

when --> if

have please --> please have