问题

at the door before you enter my room,please.
A:Knock
B:Knocking
C:Knocked
D:To knock
B:Knocking
C:Knocked
D:To knock
正确答案是:
同类题型
____ in a branch of the tree ___ a note which read"I’ll meet you at the School Gate"
If you just spend time ________ advantages and disadvantages, you may get nothing in the end. [ ]
The children ____ very quiet;I wonder what they ____ up to
I don’t think this book is very interesting.—Neither is that one.