研究细菌不常应用的动物是（）
A.小白鼠
B.豚鼠
C.家兔
D.恒河猴
E.大白鼠
参考答案：D
She doesn't like Mrs. Smith, so she always avoids ____ with her. [ ]
A. to leave alone
B. being left alone
C. to be left alone
D. being left behind
石膏的主要化学成分是
A．硫化汞
B．含水硅酸镁
C．含水硫酸钙
D．碳酸锌
E．二硫化二砷
