讨论一道PP 35 SC

小样囡

In laboratory rats, a low dose of aspirin usually suffices to block production of thromboxane,
which is a substance that promotes blood clotting, but not seriously interfering with the
production of prostacyclin, which prevents clotting.
(A) which is a substance that promotes blood clotting, but not seriously interfering
(B) a substance that promotes blood clotting, but not seriously interfering
(C) a substance that promotes blood clotting, but does not seriously interfere
(D) which is a substance to promote blood clotting, but does not seriously interfere
(E) which is a substance that promotes blood clotting, but not a serious interference  
答案是C 可是我认为是D
which is a substance to promote blood clotting和which prevents clotting. 平行 对称
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

答案为什么是C啊

edwardelric

D的问题在于，按它这么写promote和interfere就不平行了，前面用不定式，后面用第三人称单数，从语法上就变成interference和再前面的suffice平行了，意思就错了