We should plant more trees on sides of the street.A. eitherB. both C. allD. each

问题补充：

We should plant more trees on sides of the street.

A. either

B. both

C. all

D. each

答案：

A. either

(答案→)B. both

C. all

D. each

解析：句意：我们应该在街道的两边多植树。Either两者当中的一者，both两者都；all都，全部；each每一。Sides是复数名词，另根据常识街道有两个边，所以选B。