进入高空作业现场，应戴安全帽。高处作业人员必须使用安全带。
参考答案：对
— Hurry up,. The bus is coming.
— Oh, no. we mustn't cross the street ________ the traffic lights are green. [ ]
A. after
B. since
C. while
D. until
维生素K依赖因子为( )
A．Ⅱ、Ⅶ、Ⅸ、ⅩB．Ⅲ、Ⅴ、Ⅸ、ⅩC．Ⅱ、Ⅴ、Ⅸ、ⅩD．Ⅷ、Ⅴ、Ⅸ、ⅩE．Ⅲ、Ⅶ、Ⅸ、Ⅹ
