阿摩線上測驗
31、Black holes are regions of spacetime ________ gravity is so extreme that nothing, not even light, can escape.
(A) which
(B) when
(C) where
(D) whether
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統計： A(11), B(13), C(56), D(7), E(0) #2963975
統計： A(11), B(13), C(56), D(7), E(0) #2963975
