We don’t go to the cinema as much as ( D.we used to )
We don't go to the cinema (as much as we used to副词) 是对的.在这种句子的结构,是要前后呼应的.从一个惯用的角度,A,即 We don't go to the cinema (as much as we used to go),文法上没有错误,只是显示出水平较低.
B.we used to do 若要用这句在同样的结构,那前面必需用do,we don't do lunch together as much as we used to do.当然,标准的答案应该没有最后的do,即 we don't do lunch together as much as we used to.一般美国人才会说 do lunch,他们喜欢用do,这不是好的英语.
They no longer check every passenger,this is very different from what we used to do.以上是比较正常的we used to do的用法,as much as后面很少用它.
对C,前面的回答都交代了.