问题补充:
The young trees should as often as possible.
A. take care of
B. be take care of
C. be taken care of
D. be taken care
答案:
A. take care of
B. be take care of
(答案→)C. be taken care of
D. be taken care
解析:这些小树应该尽可能的受到经常的照顾。结合语境可知句子主语是动作对象,故用被动语态。选项B需变成过去分词,选项D缺少介词of。故选C。