31. We should think of ways to stop the waste from the factory _____ our living environment. 
#81053
A
being polluted
B
polluting
C
from being polluted
D
Polluted
推荐题目
You must ______ your papers before you hand them in.
#69682
A
go down
B
go across
C
go out
D
go through
As a young man,Tom used to   in the town, to find a job for a few coins.
#81651
A
knocking about;waited
B
knocked down;waiting
C
knock about;waiting
D
knocked down;waited