Had we assisted him , he us a hand today .
A. would have given ; in exchange
B. should give ; to exchange
C. could give ; in exchange
D. might have given ; to exchange for
网友回答
A. would have given ; in exchange
B. should give ; to exchange
(答案→)C. could give ; in exchange
D. might have given ; to exchange for
解析：考查虚拟语气，had we assisted him=If we had assisted him是虚拟条件句，主句是和现在相反，用could do，第二空in exchange，做为交换，句意是：如果我们帮助他，今天他就会帮我们做为交换了。选C。