流行病学实验研究中采用双盲法是为了减少（）
A.混杂偏倚
B.信息偏倚
C.入院率偏倚
D.回忆偏倚
E.选择偏倚
参考答案：B
There's only ten minutes to go. We can't wait any more- ______, we should start at once.
[ ]
A. what's more
B. in a word
C. in other words
D. in the end
列车的运行等级顺序是怎样规定的？
