Is this problem _________ the teacher explained last week A.the one B.that C.which D.one
问题描述：
Is this problem _________ the teacher explained last week A.the one B.that C.which D.one
答
A.首先这里可以看到有两个谓语,is和explained.所以必定是主从复合句.主句缺少表语,而从句是定语从句,横线处应有先行词,又由于是特指故是the one.此时定语从句的关系代词可用that,可省略.