問題詳情

136.The banking, insurance, investment, and shipping services _____ important sources of invisible earnings for the country.
(A) is
(B) are
(C) to be
(D) had been

參考答案

答案:B
難度:簡單0.777778
統計:A(10),B(49),C(0),D(0),E(0)

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