Mọi người giúp em câu này với ạ

In election, politicians try to get old people to vote for them, it is called the _____ vote.

A. white

B. blue

C. old

D. grey

Câu này ý D á bạn

bạn tính đạo hàm của f'(3-x²) ra á xong cho bằng k rồi cho các nghiệm đan dấu rồi xét 

6. The explorer who discoverd America was Christopher Columbus

7. Although he has good learning condition, he doesn't study well

8. Not until he was 40 did he marry

9. Jane speaks English better than Mary

10. Hardly did she this exercises