阿摩線上測驗
17. According to Metro safety regulations, an escalator has to be switched off if it is crowded. The descending escalator at the main station was moving at the time of accident.
(A)According to
(B)safety
(C)be switched off
(D)accident
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統計： A(0), B(0), C(0), D(3), E(0) #3313190
統計： A(0), B(0), C(0), D(3), E(0) #3313190
