SAT语法问题 than 前后的比较问题.

题目

SAT语法问题 than 前后的比较问题.
Researchers have found that large fish are most likely to countain high levels of mercury than small fish.
are more likely than fish to contain high levels of mercury.
如果原句中的most 改成more,句子有没有错?
commuters in the 1990s encountered more traffic delays than the traffic problems of the 1970s and 1980s
than commuters did in
原句为什么错?如何判断than 前后的比较对象是什么?可不可以省略成 than commuters in the 1970s and 1980s.
可不可以有高手详细讲下than前后的比较有几种说法?

答案

第一句改成more没问题了,than后面是比较状语从句省略的谓语部分,只保留主语,和前面的主语 large fish 做比较,同类比较,又都是主语,可以的.第二句90年代的人（遭遇堵车）比7、80年代的人（遭遇交通问题）要多,than前...