瓦斯爆炸有什么危害？
参考答案：
瓦斯爆炸的危害主要是：
1．产生有毒有害气体。
2．产生高温火焰。
3．此斯爆炸产生高压气体形成冲击波。
A community nurse visits a family living in a rural area where the drinking water is not fluoridated. Which of the following would the nurse suggest to the family as the most appropriate means for obtaining a significant amount of fluoride
A. Tea.B. Yogurt.C. Citrus juices.D. Natural cheeses.
钻井设备拆卸后，散件不能（）放置。
A.按吊装顺序分类
B.在平坦的地方
C.在电力线下
D.在井场面积内
