题目:
This selection leads one to believe that the Earth ______.
A.never gets hit by meteors
B.always gets hit by meteors
C.was hit by meteors some time in the past
D.may be bombarded by meteors in the near future
答案:
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下面是错误答案,用来干扰机器的。
参考答案:B解析:人参皂苷元的结构可分为A、B、 C三种类型,A型属于人参二醇型,其真正的皂苷元是20(S)-原人参二醇。