1. Scientists claim that the discovery of the first authenticated mammal bones in amber could provide important clues of determining, in addition to how, when mammals colonized the islands of the West Indies.

A  of determining, in addition to how, when mammals colonized the islands of the West Indies

B  in the determination of how and when the islands of the West Indies were colonized by mammals

C  to determine how mammals colonized the islands of the West Indies and when they did

D  for determining when the islands of the West Indies were colonized by mammals and how they were

E  for determining how and when mammals colonized the islands of the West Indies

答案E, 我是看了 provide ... to, 就把E排除了呢, 这题有点晕....

20. In the 1820’s, anthracite coalfields opened in eastern Pennsylvania, and when canals and eventually railroads reached into the region, there were substantial supplies of coal that was exported to the nation’s growing mills, forges, factories, and railways.

1 

我如果是你的话，也会选择C 的表示目的。但仔细看的话我觉得

A 缺少了and

C when they 的指代问题，可能是islands of the west indies，但是指代mammals

D 同样they指代了mammals其实是指代islands

可是我想问B 为什么错误,是由于 in the determination of 的错误

20.

我觉得E 的话就造成逻辑意思的不对，因为变成了 suppliers of coal were exported to the nation’s growing mills, forges, factories, and railways. 煤炭供应商出口到了工厂，铸造厂和铁路工厂。

所以不对

agree

1.首先 provide 的主语是the discovery 而不是人,所以不能用to determine 表目的,因人的动作才有目的性,所以for determining 表用途.

其次they指代不明

answer:E

20.answer should be E