吗啡急性中毒引起的呼吸抑制宜用：
A．咖啡因B．贝美格C．派醋甲酯D．尼可刹米E．山梗菜碱
参考答案：D
垃圾焚烧电厂二噁英产生的主要原因是（）
A.燃烧温度超过800度以后导致的。
B.生活中不同的物质中广泛存在二噁英。
C.垃圾中氯乙烯等含氯塑料的不完全燃烧而生成的。
Which of the following is least likely to be considered a necessary condition for a monopolist to realize profits from price discrimination（）
A. A product for which the demand curve is downward sloping.
B. At least two groups of customers, each with a different price elasticity of demand.
C. Two different costs of production.
