单项选择题

Many a plan ______ to fight against pollution.

A．have been worked out
B．have been worked on
C．has been worked out
D．has been worked on
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单项选择题
All too ______ it was time go back to work after the Spring Festival.
A．often
B．quick
C．soon
D．fast
单项选择题
______ difficulties we may have, we must finish the task as required.
A．Whatever
B．Whichever
C．Of which
D．No matter how
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