阿摩線上測驗
1. Unlike competitive runners, race walkers ____ some portion of their feet in contact with the ground.
(A) must to always keep
(B) must always keeping
(C) always must to keep
(D) must always keep
(E) always must keeping
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統計： A(1), B(8), C(3), D(19), E(0) #1093363
統計： A(1), B(8), C(3), D(19), E(0) #1093363