用括号内所给词的适当形式填空The trees must ______(water)three times a week at first.

问题描述:

用括号内所给词的适当形式填空
The trees must ______(water)three times a week at first.

be watered;
被动语态,每天被浇水,water在此做动词表示浇水。

be watered 被浇水.