题目

Some people say that childhood is the best time of your life._______, being a child has both advantages and disadvantages.On the good side, you have very few responsibilities. For example, you don’t have to go to _______, pay bills, or do the shopping, cooking, or cleaning. This _______ you have plenty of free time to do whatever you want — watch TV, play on the computer, go out with friends, play sports, or enjoy other _______. On top of that, public transport, cinema, and sports centers _______much less for children. All in all, being a child is an exciting time in life.However, there ar一定质量的某有机化合物在空气中完全燃烧，生成二氧化碳和 水，由此可以确定该有机化合物的组成（　　） A、只含有碳和氢两种元素B、含有碳、氢、氧三种元素C、一定含有碳、氢两种元素，可能含有氧元素D、无法确定