Stop! You can never touch this machine when it ________, it is very dangerous. 
#102729
A
has been operated
B
will be operated
C
is operated
D
is being operated
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If city noises ___from increasing, people __ shout to be heard even at the dinner table 20 years from now.
#103976
A
are not kept; will have to
B
are not kept; have to
C
do not kept ; will have to
D
do not keep; have to
 I ____ Mr. White at that time, otherwise I wouldn’t have asked you for some information about him. 
#101527
A
hadn’t known
B
don’t know
C
didn’t know
D
haven’t known