在革兰染色中，石炭酸复红或沙黄染液起的作用是（）
A.初染剂
B.复染剂
C.脱色剂
D.媒染剂
E.固定剂
参考答案：B
车辆通过铁道路口时，应用低速挡安全通过，中途不得换挡，以避免发动机熄火。
It was from only a few supplies that she had bought in the village _____ the hostess cooked such a nice dinner. [ ]
A. where
B. that
C. when
D. which
