强直性脊柱炎首先侵犯的是（）。
A.腰骶关节
B.骶髂关节
C.髋关节
D.膝关节
E.腕关节
参考答案：B
The professor suggested that the students ________ into four groups in the experiment. [ ]
A. be divided
B. must divided
C. might divided
D. should divided
社会生物学主要基于（）
