4.I find it difficult to ________ on my work when there is too much noise around me.
(A) concentrate
(B) converse
(C) conclude
(D) appoint
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統計: A(9), B(2), C(0), D(0), E(0) #3890910
統計: A(9), B(2), C(0), D(0), E(0) #3890910