Each of functions (A) of the body (B), even thinking, requires the expenditure (C) of energy (D).
答案 A。
水妖笔记中解释each of 后面加单数，改成 each of function。可是，我看金山词霸中each of 后面是接复数的，如：Each of his children ，each of us，Each of the suites 。
请问each of 后面 是接名词单数还是复数呀？
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