1. a. studies

b. wrote

c. is sleeping

d. was, am

2. a. (-) my mother doesn't always give me a present for my birthday.

(?) does my mother always give me a present for my birthday?

• yes, she does
• no, she doesn't

b. (-) he didn't know the answer of the question

(?) did he know the answer of the question?

• yes, he did
• no, he didn't

3. a. my mother fries chicken meat every sunday

b. my mother is frying chicken meat now

c. my mother fried chicken meat last sunday

4. cheaper, more expensive

5. heavy, heavier, heaviest

6. the text tells us about customer's embarrassing experience.

7. the manager is generous and responsible

8. the security officer

9. b, c, a, d, f, e, g

10. I played football yesterday, she drank ice tea yesterday, my sister read novel yesterday, he thought about her yesterday, hana fell from the bicycle yesterday

semoga membantu! :D