All we have to do_____ learn by heart.里填那个（A.is to B.to C.are to D.be to)
问题描述：
All we have to do_____ learn by heart.里填那个（A.is to B.to C.are to D.be to)
答
A
all在这里没有具体说什么,所以看成一个抽象的东西,当成不可数名词,后用is,is后的表语或者是不定式,或者是动名词,所以A