---The book is borrowed from the library. You ____ your children touch it with their dirty hands. ---Sorry.    
#88042
A
should have let 
B
needn’t have let 
C
mustn’t have let
D
ought not to have let
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The workers demanded that their employer_____ their working conditions. 
#86737
A
had improved
B
would improve
C
improve
D
will improve
It is required that no smoking ______ in the school.
#89784
A
was allowed
B
be allowed
C
would be allowed
D
had been allowed