是以前摘录的,无法知道出处了.非常对不起不能用统一格式.

1.By studying fossils, paleontologist learn ___ forms of life thrived during various period of the earth's history.

A.from

B.so

C.the.

D.what

答案D. 为什么?为什么不是C.

2. Beginning in the middle Ages, composers of western music used a system of notating their compositions ___ be performed by musicians.

A. will

B.that.

C.and when to

D. so they could

答案D. 怎么不是so that they could?

3. The production of tin ore in the United States is relatively insignificant, ___less than one hundred tons annually.

A. amounting to

B. in the amount

C. amounts to it

D. to the amount of

答案A, 为什么B,D不对?

1.ＴＨＥ这里指代不清，前面没有提到哪种ＦＯＲＭ所以不选，ＣＷＨＡＴ是learn的宾语，又是thrived的主语．

2 ＴＨＡＴ是可以省得

3 amount to 是各词组表总计，这里也符合句意，若把ＡＭＯＵＮＴ当名词解释这个意思后需有ＯＦ，Ｂ不对，但Ｄ中ＯＦ后又无中心词，所以不选．