35.
In laboratory rats, a low dose of aspirinusually suffices to block production of thromboxane,
which is a substance that promotes bloodclotting, but not seriously interfering with the
production of prostacyclin, whichprevents clotting.
(A) which is a substance that promotesblood clotting, but not seriously interfering
(B) a substance that promotes bloodclotting, but not seriously interfering
(C) a substance that promotes bloodclotting, but does not seriously interfere
(D) which is a substance to promote bloodclotting, but does not seriously interfere
(E) which is a substance that promotesblood clotting, but not a serious interference
Prep07语法笔记说:
(C) 正确, a substance that…同位语结构，作为thromboxane的同位语对thromboxane进行解释
说明; but does跳过同位语和suffices并列共同作为a low dose of aspirin的谓语动词
(D) but does…更像是跟is a substance…并列,从而作为了thromboxane的谓语动词,改变了原句
的意思
可以理解D说更像和is a substance并列，但是，为什么C中but does就跳过同位语和suffices并列了呢？在我看来，非常像和 that promotes并列了啊。
还有一个问题，but作并列的时候，是不是和and类似？这里如果but后能够有指代主句主语的代词it，我觉得才像是和主句并列啊...
求指教！谢谢
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