21．---- Do you surf the Internet a lot？
---- Well,_______, I’m too busy with work to surf the Net.
A. all right B.I have no idea C. at last D. to tell you the truth
22.Visiting _______ Great Wall is ________ unforgettable experience to me.
A. /; / B. /; an C. the; an D. the; /
23. The message is very important, so it is supposed _______ as soon as possible.
A. to be sent B. to send C. being sent D. sending
