問題詳情

43. Why do swine flu viruses change constantly?
(A) The weather in the United States is changeable.
(B) The symptoms of swine flu change in different seasons.
(C)Influenza viruses from different species exchange their genes.
(D) The main virus subtypes change their genetic structures automatically.

參考答案

答案:C
難度:簡單0.772277
統計:A(3),B(5),C(78),D(14),E(0)

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