______ the sight was impressive on the top of the mountain, I made an effort to climb onto it．
A． To know B． Know
C． Known D． Knowing
We still have some other ways to solve the problem．You ______ be worried．
A． mustn’t B． can’t
C． don’t have to D． may not
Harry Potter has made reading popular again, ______ is why parents and teachers like the book, too．
A． that B． who
C． which D． what
Some countries have banned smoking in public places ______ public health．
A． improve B． to improve
C． improving D． improved
Mr．Smith had to go to work by bus this morning as his car ______．
A． would repair B． was repairing
C． had been repaired D． was being repaired
Food and fruit are forbidden in the library, ______ you are allowed to have drinks and sweets with you．
A． and B． but C． so D． or
