问题

_____ your letter, I would have written back two days ago. [ ]
A: If I received
B: Should I receive
C: Had I received
D: If I could have received
B: Should I receive
C: Had I received
D: If I could have received
正确答案是:
同类题型
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ad_____yourtestpapercarefullybeforehandingitin,youwouldhavemadefewermistakes.