还是英语Volcanoesaredividedintothreemaingroups,basedontheirshapeandthetypeofmaterialthey.(A)aremade(B)madeof(C)aremadeof(D)madefor答案说A和D可以先排除（为什么?）并且可以判断不是whicharema

Question

还是英语
Volcanoes are divided into three main groups,based on their shape and the type of
material they __________ .
(A) are made
(B) made of
(C) are made of
(D) made for
答案说A和D可以先排除（为什么?）
并且可以判断不是which are made of 的省略结构,否则之前的they没有用（这是怎么判断的?）所以排除B（为什么知道不是这个结构就能排除B了?）

Answer 1

如果选A的话,they are made这个结构中,they 已经是made的宾语,那么这个结构就已经完整,是个完整的句子,那跟前面的material怎么产生联系呢?所以要有一个of,构成be made of短语,意为：由.制成.那么material就变成of的...