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题库 / OG2018-SC-699
Researchers now regard interferon as not a single substance, but it is rather a biological family of complex molecules that play an important, though not entirely defined, role in the immune system.
as not a single substance, but it is rather a biological family of complex molecules that play
as not a single substance but as a biological family of complex molecules playing
not as a single substance but as a biological family of complex molecules that play
not to be a single substance but rather a biological family of complex molecules playing
not as a single substance but instead as being a biological family of complex molecules that play
最后那个play，为什么不是plays呢？这个没太弄明白。
语义应该为complex molecules (而不是 a biological family ) play an important role in the immune system
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