能初步鉴别致病性肠道杆菌与非致病性肠道杆菌的试验是()
A.葡萄糖发酵试验
B.乳糖发酵试验
C.VP试验
D.甲基红试验
E.枸橼酸盐利用试验
参考答案:B
一元二次方程(1-k)x2-2x-1=0有两个不相等的实数根,则k的取值范围是( )
A.k>2
B.k<2且k≠1
C.k<2
D.k>2且k≠1
In England, traffic keep to the left. It's different from that in China. [ ]
A. must
B. may
C. can
D. need