Earth is a rocky planet__liquid water,which is necessary for life ,can exist.
问题描述：
Earth is a rocky planet__liquid water,which is necessary for life ,can exist.
A.as B.when C.which D.where
答案选D,为什么?求解释.
答
where 在这里相当于 on the earth=on which (which 指代地球),它作地点状语
做这种题有个简单的方法直接看后面的liquid water,可以确定跟时间无关,所以排除when.
如果liquid water后可直接加前面的Earth就选which,如果需要加介词in,on等,则选where.