Silver is the best conductor of electricity, copper _______ it closely．

A． followed            B． following          C． to follow            D． follows

Many young people in the West are expected to leave _____  could be life’s most important decision—marriage—almost entirely up to luck．

A． as              B． that                 C． which             D． what

______ his telephone number or e-mail address, she had some difficulty ____ in touch with John．

A．Not knowing; getting                         B．Not having known; to get

C．Knowing not; to get                         D．Having not known; getting

Tom often has to be called several times ______ he comes downstairs for dinner．

A． before         B． until            C． when         D． then

What I need is nothing but a book, _________ that can help to kill the time tonight．

A． it       B． that         C． one          D．the one

________ , but it is also a good idea to reduce the potential dangers．

A． Not only a fun thing is it to do                B． Not only a fun thing to do it is 

C． Not only it is a fun thing to do                  D． Not only is it a fun thing to do

Don’t play computer games too often, for once ________ them, you will suffer later on．

A． adapted to            B． addicted to         C． adjusted to          D． applied to

—How did you know the details of that surprising news?

—I happened _________ the event then．

A．to be listening                                  B．to have covered

C．to be covering                                   D．to have listened

In the time of economic crisis, every coin _________ a lot．

A． values       B． important           C． worth         D． counts

—Why can your teacher know so much about London?

—He ________ have been there before．

A． may         B． must         C． ought to         D． should