题目

常温下，已知:CH4(g)+2O2(g)=CO2(g)+2H2O(1)∆H=-980kJ/mol 2H2(g)+O2(g)=2H2O(1) △H=-560kJ/mol 现有CH4和H2组成的混合气体共0.4mol,使其在O2中完全燃烧，恢复至常温共放出252kJ的热量，则CH4与H2的物质的量之比是（） A . 1:1 B . 1:2 C . 2:3 D . 3:2 答案：AThey only stood there with their arms ______ in front of their chest rather than give us a hand.A．foldingB．foldedC．to be foldedD．being folded