3 TOEFL GRAMMER Q~ From Taiwan

fernandochang

Here are 3 real Qs from Taiwanese Cram School~ Could anybody explain me the reasons? Thanks~
APEX TOEFL GRAMMER QUESTIONS Unit 7
3.The Empire State Building in NY enjoyed the distinction----------the highest building in the world until 1970, when the World Trade Center was completed.
(A)which was
(B)of
(C)since
(D)because it was
A)

5.Paris is renowned both as the political center of the nation and as --------------.
(A)the cultural center also
(B)a center of cultural activity
(C)being a cultural center
(D)to be a center of cultural activity
A):B

6.The photovoltaic cell provides us with---------energy directly from the sun, but also to solve the problem or environmental pollution.
(A)not the ability only to produce
(B)the ability to produce not only
(C)the ability not only to produce
(D)not only the ability to produce
A):C

redli

1)(A)which was---which指代不清，可以是Building 也可以distinction
   (B)of--不合句意
  (C)since--缺主谓
  (D)because it was----因果关系，句子完整，正确
2）C，D肯定错，
    (A)the cultural center also--- also多于，前面已经是个完整的not only...but also 句子
     B)a center of cultural activity---标准对称句，正确
3） not only to。。。 but also to -----对称