27. It is dangerous ____ your seatbelt fastened during the
entire flight.
(A)to keep
(B)that keeping
(C)not to keep
(D)to not
keeping
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統計: A(16), B(15), C(74), D(25), E(0) #3287576
統計: A(16), B(15), C(74), D(25), E(0) #3287576