单项选择题
It is assumed that students at an intermediate level will have a good（）of the basic structures and vocabulary of English.
A.command B.commanding C.to command D.commanded
单项选择题 I am pleased to take（）to exchange views with you.
单项选择题 Please leave the key under the door（）you go out.
单项选择题 We have kept（）our friendship by writing to each other, so we are true friends.
