单项选择题

First aid can save a person's life if ______ immediately and properly.

A．perform
B．performing
C．performed
D．to perform
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单项选择题
The old man, ______ abroad for twenty years, is on the way back to his motherland.
A．to work
B．working
C．to have worked
D．having worked
单项选择题
When do you think ______ visit her uncle
A．she was going to
B．will she go to
C．she will go
D．she will go to
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