这里it 我不同意因为根据ron的语法课上说的原则,
GMAT can tolerate pronoun ambiguity if:
the context is obvious
the pronoun is parallel to the intended noun
the pronoun is not parallel to the other noun
这个it是正确的--我觉得只是这个时态的问题,应该是had
在听Thursday with Ron. Tommy有讲这个题:
B错最大的问题是语意不对。按照选项的意思,这里主要强调的是imaginary,但并不是科学家们相信这个物质是imaginary的,而是相信combustion released phlogiston。
C的话也是语意问题:直到A.L.证明了之后,phlogiston才是一种imaginary substance吗?显然不对,因为phlogiston一直是imaginary的。
D中,后半句was believed by scientists to be released by combustion用了太多被动语态和modifiers,整个句子很别扭
E中,scientists believe...phlogiston was an imaginary substance...错误同B;而且用了太多被动语态。