阿摩線上測驗
18. They _____ for three hours before they finally found the lost dog.
(A) search
(B) searching
(C) are searching
(D) had been searching
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統計： A(0), B(3), C(4), D(86), E(0) #3440478
統計： A(0), B(3), C(4), D(86), E(0) #3440478
