46. According to the passage, what is the main advantage of reusable rockets?
(A) They land more efficiently.
(B) They are cheaper.
(C) They use solar power to refuel.
(D) They are bio-degradable.
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統計: A(0), B(0), C(1), D(0), E(0) #3370846
統計: A(0), B(0), C(1), D(0), E(0) #3370846