3.
(A) at times
(B) at a time
(C) make time
(D) before long

答案：登入後查看
統計： A(28), B(101), C(10), D(1), E(0) #589482

詳解 (共 2 筆)

#995084
at a time  一次(幾個)

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#5414549

key words: In one experiment →  at a time

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