Properly _______ with numbers, the books can be easily found.
#97433
A
marked 
B
mark  
C
to mark  
D
marking
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This is one of the problems_____ at the meeting at present.
#94802
A
discussed
B
discussing
C
to be discussing
D
being discussed
We’ve come to help. Which room do you want ______? 
#97422
A
cleaning
B
cleaned
C
to clean
D
to be cleaned