50. Which is true about Auroras?
(A) They can only appear as arcs or swirls.
(B) The most spectacular ones are most often viewed in Japan.
(C) They appear to be in motion once in a while.
(D) The collision of some particles causes quantum leaps.
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統計: A(12), B(30), C(94), D(331), E(0) #1806268
統計: A(12), B(30), C(94), D(331), E(0) #1806268