我国成人硒的推荐摄入量（RNI）为（）
A.50μg／d
B.100μg／d
C.150μg／d
D.200μg／d
E.500μg／d
参考答案：A
地球上出现的四季更替是由于（）
The ______ Method believes grammar is learned inductively through listening and speaking activities.
