_____ does he go to school on weekdays? [ ]

A. What      

B. What time    

C. Why      

D. What about

实验小鼠首选的麻醉方法是（）。

A.肌肉麻醉

B.腹腔麻醉

C.吸入麻醉

D.皮下麻醉

E.静脉麻醉