双极细胞核位于哪一层()
A．视锥、视杆细胞层
B．外核层
C．神经节细胞层
D．内核层
E．神经纤维层
参考答案：D
31. We should think of ways to stop the waste from the factory _____ our living environment.
A．being polluted
B．polluting
C．from being polluted
D．Polluted
有疏肝理气功效的解表药是（）
A.蝉蜕
B.牛蒡子
C.薄荷
D.葛根
E.菊花
