To develop more accurate population forecasts , demographers have to know a great deal more than now about social and economic determinants of fertility.
A. have to know a great deal more than they do now about the social and economic
D. would have to know a great deal more than they do now about the social and economic
答案是D，我选A
请问这里又没有虚拟条件，To develop…只是表目的，为什么要用虚拟would have to而不是have to?
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发表于 2006-10-16 19:16:00
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