He has been        the computer for two hours, chatting with a boy from Australia.

A. in B. on          C. at  D. by

The listeners were much        than hoped. There were so many tickets left.

A. fewer   B. larger      C. more D. less

         — Are you expecting to receive a digital camera as a gift?

— Yeah! I can’t wait to get       .

A. some    B. any        C. it                                    D. one

 — She looks rather upset. She        the exam.

— I guess so. It’s very difficult after all.

A. must have failed   B. can fail

C. would have failed D. should fail

— Jim has gone to Britain to see a modern art exhibition.

— Oh, really? Do you know when he       ?

A. leaves   B. will leave       C. was leaving   D. left

 It is already well understood        causes the global warming.

A. what     B. when    C. that       D. how

 Visitors to the hills are greeted by signs        them to look out.

A. warn     B. to warn C. warning         D. warned

       she was out of the room, he took a quick look at the papers on her desk.

A. If  B. While    C. Though D. Unless

In the past several weeks, many cities in Northern China        from heavy fogs and     severe cold.

A. had suffered          B. have been suffering     C. were suffered     D. suffered

 Don’t litter in the street in Singapore,        you could be arrested.

A. or B. and        C. but        D. so