属于区分葡萄球菌属和链球菌属的试验的是（）
A.VP试验
B.吲哚试验
C.氰化钾试验
D.硝酸盐还原试验
E.触酶试验
参考答案：E
Once he has determined _____ something, no one can change his mind. [ ]
A. to do
B. doing
C. to have done
D. having done
为何要对液硫进行脱气处理？
