下列模型不属于毒物伤害模型的( )。A．液体泄放速度模型 B．烟团模型 C．电子装

世界卫生组织（）年曾经给健康促进做以下定义：“健康促进是促进人们维护和提高他们自身健康的过程，是协调人类与他们环境之间的战略，规定个人与社会对健康各自所负的责任。”

A.1985

B.1986

C.1987

D.1988

We have a PE class ______ the afternoon every day.[ ]

A. in        

B. on        

C. at        

D. of

Passage 1 The US dollar value of Chinese exports increased at an average rate of almost 18 per cent per annum between 1978 and 1983, while imports increased by approximately 11 per cent per annum. As a result, the visible trade surplus rose sharply from US $1.4 billion in 1981 to US $4.4 billion in 1982 and US$3.7 billion in 1983. Exports grew much faster than imports during this period not only because of the p emphasis placed on exporting by China’s economic planners, but also because a number of industrial projects were postponed in 1979. Official recognition that foreign technology could play a major role in modernising the Chinese economy had caused imports to rise by more than 50 per cent in 1978 placing undue strain on the national economy. Grain imports have fallen sharply over the past few years—China became a net grain exporter in 1984—and in 1983 the country started to export soyabeans and cotton.

Why did the more than 50% rise in imports of 1978 place undue strain on China’s national economy

氨的接触催化氧化反应4NH₃(g) +5O₂(g)4NO(g)+6H₂O(g) △H=-1025 kJ/mol是工业上制备硝酸的重要反应。一定条件下将4 mol NH₃和5 mol O₂混合于固定容积为2L的密闭容器中，经10s该反应达平衡，并测得NO的浓度为0.8 mol/L。下列判断正确的是 [ ]

A．达平衡时，2v_正(NH₃)=3v_逆(H₂O)

B．反应达到平衡状态时NH₃的转化率为20%

C．升高温度能使减小

D．将容器的体积变为4L，平衡时NO的浓度小于0.4 mol/L

目标准则的确定应考虑哪些因素？