新人求助><2017OG上的几个题目！！

rosarosalyn

打出了正确的句子，红色标的是不理解的地方！谢谢大佬们

731. To develop more accurate populationforecasts, demographers would have to know（为什么用虚拟语气？） a greatdeal more than they do now about the social and economic determinants.

还有关于比较的问题，弄不清。。。

758. Price at the producer level are only 1.3 percent higher now than those of a year ago.

772. Heating-oil prices are expected to behigher this year than last（为何不是同758，thoseof last year??） because refiners are paying about 5 dollars more forcrude oil than they were last year.

777也是同一种题，没打出来。和772类似，than后面都没有用those of ..的形式

我晕了……到底怎么看than前后的结构呀！！！

求答疑，谢谢！

rosarosalyn

顶顶。。

rosarosalyn

不死不灭不成神

你应该把题目都贴出来哦，因为答案是比出来的，有时候两种结构都可以，是别的地方出了问题，
可以看看这个帖子
https://forum.chasedream.com/thread-1254455-1-1.html