阿摩線上測驗
7. A hot air balloon will rise when its density is ________ of the surrounding air.
(A) than the lower density
(B) the density is lower than
(C) lower than that
(D) the lower density
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統計： A(26), B(30), C(263), D(34), E(0) #2154303
統計： A(26), B(30), C(263), D(34), E(0) #2154303
