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? | 
