He walked down the hills, ____ softly to himself.　　
　 A. sing　　　         B. singing　　　         C. sung　　　         D. to sing

 At this moment the bell rang 　____ the end of class.　
　 A. announce　　　     B. announcing　　 C. announced　　　         D. to announce

 The child sat in the dentist's chair ____ .　　
　 A. tremble　　　  B. trembling　　　         C. trembled　　　         D. to trembled

 Properly ____ with numbers, the books can be easily found.
　 A. marked　　　         B. mark　　　         C. to mark　　　         D. marking

 Were you ____ when you saw that wild animal?　
　 A. fright　　　   B. frightening　　　         C. frightened　　　         D. frighten

 ____ the composition, John handed it to the teacher and went out of the room　
　 A. Writing　         B. Having written 　        C. Written　　　         D. Being written

 "Can you read?" Mary said ____ to the notice.　
　 A. angrily pointing　   B. and point angrily　 C. angrily pointed  D. and angrily pointing

The visiting Minister expressed his satisfaction with the talks, ____ that he had enjoyed his stay here.
　 A. having added　 B. to add　　　 C. adding　　　 D. added

 "We must keep a secret of the things ____ here", the general said, ____ 　at the man in charge of the information office.　
　 A. discussed, stared seriously 　        B. being discussed, seriously staring
　 C. to be discussed, seriously stared 　        D. discussed, stared

 China is one of the largest countries in the world, ____ 9.6 million square (平方) kilometres.
A. to cover　　　         B. covered　　　         C. covers　　　         D. covering