XY13-1的第32题

greatvampirer

Q32:

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

1. have to know a great deal more than now about the social and economic
2. have to know a great deal more than they do now about the social and economical
3. would have to know a great deal more than they do now about the social and economical
4. would have to know a great deal more than they do now about the social and economic
5. would have to know a great deal more than now about the social and economical

请问为什么B不对而E对？为什么一定要用WOULD HAVE TO KNOW时态？

qiancheng

It's D.

首先：economic VS economical 排除 economical的所有选项

其次：时态上应该用would have to。

再次：THEY DO 不能省~