When he looked up, he suddenly found himself          by a group of teenagers, 
#95568
A
to be surrounded;
B
surrounded;
C
be surrounded;
D
having been surrounded;
推荐题目
 _____ what would happen,none of them could find a way out. 
#90766
A
Left wondering
B
Having left wondering
C
Leaving to wonder
D
Having left to wonder
Each button, when ____, provides a piece of beautiful music.
#88692
A
clicked
B
having clicked
C
clicking
D
being clicked