We don’t think the experiment is ___ failure. At least we have gained ___ experience for future success.

A．the; a

B．a; /

C．a; an

D．the; the

毒理学实验中，Ames试验的指示菌株是（）

A.鼠伤寒沙门菌的野生型菌株

B.鼠伤寒沙门菌的色氨酸突变型菌株

C.鼠伤寒沙门菌的组氨酸突变型菌株

D.大肠杆菌的野生型菌株

E.大肠杆菌的色氨酸突变型菌株