31 Dr. Lee kept ______ doing the same experiment over and over again.
(A)in
(B)on
(C)away
(D)with

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統計： A(30), B(77), C(10), D(7), E(0) #2788294

詳解 (共 1 筆)

#5215424


keep on doing sth  繼續做；反覆做

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