<--[if !supportLists]-->178.<--[endif]-->Biologists believe
that they have found one of the substances that tell individual genes both
when to become active and when to remain quiescent in the earliest phases
of an embryo’s development.
(A) tell individual
genes both when to become active and when to remain
(B) tell individual
genes both at which time they should become active or should remain
(C) tells
individual genes both when to become active or remain ********
(D) tells
individual genes both when to become active or when to remain（A）D-22
(E) will tell an
individual gene both about when it should become active and remain
答案a没有问题，我想问的是一个语法点：one of ＋复数n.＋v.复数，the only one of ＋复数n.＋v.单数，是这样么？？跟单数还有什么类似的情况？？
谢谢！！
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