the trees on both sides of the road need____(water) three times a week,or they will die
问题描述：
the trees on both sides of the road need____(water) three times a week,or they will die
答
to water
答
need watering=need to be watered
这里need+doing表被动
不客气地说，楼上两位有误，sorry for that.
答
to be watered 被动语态
答
water