题目内容:
Whatisthemainthesisofthearticle? A.Volcaniceruptionsarenotalwaysdeadly.
B.Oldervolcaniceruptionsweremoredestructive.
C.Carbondioxideemissionsoftengiverisetoglobalwarming.
D.Itisnoteasytocalculatethekillingpowerofavolcaniceruption.
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答案解析: