He knows to study at his best, so he still does a good job even when he spends as much time playing

computer games as he _________. [      ]

A. is studying  

B. does studying  

C. has studying  

D. studies

电解质分析仪中需要设定程序的是（）

A.监察分析仪稳定性

B.调校自动定标频率

C.操作者日常保养

D.选择自动或手动定标方式

E.自动分析检测