实现安全第一的重要手段是（）。
A．安全培训
B．安全设施
C．增加投入
D．预防为主
参考答案：D
1. We won't know whether it will be successful. We won't know whether there will be good _____.
A. ends B. results C. effects D. causes
2. He's the kind of man who is fond of _____ compliments to other men's wives.
A. paying B. saying C. expressing D. showing
A．
闻气体的气味
B．
用浓硫酸干燥氢气
C．
向容量瓶中转移液体
D．
检验钾元素的存在
