OG12-41 不懂的细节真是越来越多了

winny0821

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

A.have to know a great deal more than now about the social and economic
D.would have to know a great deal more than they do now about the social and economic

正解是D。对于A，我有两个不懂：1.为什么have前面要加would？ 2.OG说A选项把knowledge和time做比较了，可是只有一个a great deal，后面没有跟of sth，那我就很自然的以为它是省略掉of sth了，所以看到后面的now，也就很自然以为now那里也是省略掉名词了，所以觉得这两个比较对象是可以被对比的。为什么这样不对呢？而且对于D选项，它也是a great deal 和 they do比较，为什么这两个就可以比较呢？

banglixing

加would是因为不定式也可以表虚拟；这题关键是要搞清楚比较对象。
主谓宾的比较如这题。they would have to know...more than...they do now. 需要把比较对象的主谓补齐。
是将来they have to do与现在they do做比较。
而A，变成they have to do与now做比较显然不对

zhaoyiqing

为什么不能理解成是省略呢？OG后面93题说Heating-oil prices are expected to be higer this year than last because.......
这个是对的，那than now 怎么就不对了呢

crystalbain

a great deal做副词，修饰比较级more