一道同义句转换（初二英语）
问题描述：
一道同义句转换（初二英语）
We ought to do something to keep the rivers clean.
____ ____ ____ ____ ____ to keep the rivers clean.
答
we should have done something to keep the rivers clean .我们本该做些事去保持河水清洁.should have done sth= ought to 本该做某事而没去做.