demographers would have to know 应该是主句来的吧,不是条件句。to develop ... 做目的状语。
如果把后面看作条件从句,那么全句结构不完整了。
这里的 would 应该是主句中用到了虚拟语气。
-- by 会员 sayysong (2009/12/10 12:12:43)
To develop more accurate population forecasts,demographers
would have to know a great deal more than they do now about the social and economic determinants of fertility.
现在这个句子是正确的,我想问的是would在这里表示的是一个含蓄条件句么?
-- by 会员 zylrt (2009/12/10 10:31:19)