题目

用燃气灶烧水，燃烧0.5kg的煤气，使50kg的水从20℃升高到70℃．已知水的比热容为4．2×103J／(kg·℃)，煤气的热值为4．2×107J/kg．求：(1)0.5kg煤气完全燃烧放出的热量．(2)水吸收的热量． (3)燃气灶烧水的效率． 答案：书面表达请阅读下面短文，并按要求以Our Life Rests on Our Choice为题，用英语写一篇150词左右的文章。Life is a matter of choice. Seemingly, it means a choice of concrete (具体的) things. But in fact, it means choosing a way of life. Life is to be lived and enjoyed, not to be wasted or complained about.Hardly can we forget the time when our society faced the threat from the life-and death disease --- SARS. Yet, even during those dreadful times, some suffering people remained optimistic. Instead of wearing white masks, some people turned to color1 ful ones, and thus displayed a happy mood. And some creative people dubbed SARS to mean “SMILE AND REMAIN SMILING.” People who survive these kinds of circumstances decide in their minds to carry on in spite of the hardships.Although we cannot choose our appearance, inborn gifts and even avoid unexpected disasters and adversities (逆境), we do have the right to choose to live optimistically, to love our lives, to have dreams, and to cherish hopes.Every morning when we get up, we have a choice of how we want to approach life that day.【写作内容】1. 用约30个单词写出上文的概要；2. 用约120个词就“Our Life Rests on Our Choice” 谈谈你的看法和感受，内容包括：（1）简要叙述你对“Our Life Rests on Our Choice”的理解；（2）请举例说明你会选择怎样的人生态度；（3）简要叙述你这样选择的理由。（至少2点）1.阐述观点或提供论据时，不能直接饮用原文语句；2.作文中不能出现真实姓名和学校名称。内容完整，语言规范，语篇连贯，词数适当。