OG12-41

aman8da

41, To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic deterninants of fertility

B. 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，请教为什么要用虚拟语气？

lumanyu

个人觉得突出了与now的情况的比较，强调了now的不足。

chilinvision

为了实现一个目的，而应该要怎么样。强调一种建议而用的虚拟语气

而且B选项中economic变成economical,改变了原意

duducrystal

up

jyy529

To develop more accurate population forecasts是一个没有实现的情况，不是现实，而是自己的假象情况，所以要用条件语气表现这种非现实

lzj1209

我觉得这里would不是虚拟语气的用法~

而是情态动词的用法~

表达了一种未来可能发生的事~

refer to a promised but uncertain future event~

chenche8827

是不是可以这样想呢？加上我们通常会用到的if then的句型，原句改为（if demographers want） to develop more accurate population forecsts，（then）they would have to know a 。。。。这是不是OG所说的虚拟语气的意思呢？是虚拟条件句没有用if来表达，用的是一个表目的介词短语。。