题目

At the end of my first year of high school, I realized I needed to find a summer job. I was tired of having to ask my parents for _________ . I wanted to go to the shopping center or movies with friends without having to ask for $20 from my parents. I imagined having a job at a store or at a summer camp where I could play games with children. But what actually happened was _________. The only job I managed to find was cleaning up tables at a local restaurant. At first, the idea of clearing tables upset me. The thought of getting up at dawn(黎明) to go clean up after people made me _______ ev 构成物质的基本成分 古希腊学者曾经提出过一个学说：复杂的物质世界是由“水、木、火和空气”四种基本成分组成的，也称“四元素学说”．十八世纪末，科学家通过实验证明了空气中含有氧气和氮气及通电分解水能产生氧气和氢气，该学说被彻底否定． （1）从现代物质组成的理论看，在水、土、火和空气中，属于纯净物的是　．属于混合物的是　，火（填“属于”或“不属于”）　　物质． （2）从化学变化的理论看，组成物质世界的基本成分是，水通电分解的化学方程式为