求NN解释，前后比较如何省略

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

l Soaring television costs accounted for more than half the spending in the presidential campaign of 1992, a greater proportion than in any previous election.

第一句话不对，now应该改成they do now

第二句话对，可以省略

有疑问的是：

1.如果第一句话在前面加上in the future等时间词那么是不是只用now也可以，比如：

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

因为比如这样的例子：The animosity between those who regulate and those who are regulated has never been more pronounced than in recent debates over environmentalism and pollution control.这句话就是对的，因为never和 in recent debates相对应

2.如果第二句话in去掉的话：

Soaring television costs accounted for more than half the spending in the presidential campaign of 1992, a greater proportion than any previous election.

那么是不是就不对了呢？

真的很混乱，求大神拍醒