If you can't decide which of the two books to borrow, why don't you take _____?

I won't read them this week. [ ]

A. all

B. any

C. either

D. both

每（）至少一次对采气树进行一次上漆，在涂刷底漆前，应对其表面进行彻底除锈，且表面无油脂、焊渣、砂尘、露水及其它污物。

A.一年

B.半年

C.一季度

D.两年