阿摩線上測驗
16. The volunteers were given orders to contact the command center _______ anything alarming happen.
(A) must
(B) should
(C) ought
(D) would
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統計： A(32), B(123), C(49), D(65), E(0) #2297934
統計： A(32), B(123), C(49), D(65), E(0) #2297934
