—Where is Jack? —He basketball on the playground. A. plays B.is going to play C. is playing D. play 答案:C下列有关叙述正确的是A.稀有气体的晶体其组成微粒是原子,晶体中不存在分子间作用力B.金刚石的熔、沸点高于晶体硅,因为C—C键能大于Si—Si键能C.CO燃烧的热化学方程式可表示为:CO(g)+O2(g)CO2(g);ΔH=+283 kJ·mol-1D. C-12的原子组成符号为C,二氧化碳分子的结构式为O=C=O