问题
选择题
下列反应属于吸热反应的是（ ）
A．石灰石分解
B．生石灰溶于水
C．锌放入稀硫酸中
D．碳不完全燃烧
答案
A、石灰石在高温下的分解反应是吸热反应，故A正确；
B、生石灰与水反应放出大量的热，则属于放热反应，故B错误；
C、金属和酸的反应是放热反应，故C错误；
D、物质的燃烧反应是常见放热反应，故D错误．
故选A．
搜题请搜索小程序“爱下问搜题”
下列反应属于吸热反应的是（ ）
A．石灰石分解
B．生石灰溶于水
C．锌放入稀硫酸中
D．碳不完全燃烧
A、石灰石在高温下的分解反应是吸热反应，故A正确；
B、生石灰与水反应放出大量的热，则属于放热反应，故B错误；
C、金属和酸的反应是放热反应，故C错误；
D、物质的燃烧反应是常见放热反应，故D错误．
故选A．
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| The yearly Marathon in my town usually happened during a heat wave. My job was to follow behind the runners in an ambulance (救护车) 1 any of them needed medical attention. "We're supposed to stay behind the 2 runner, so take it slowly," I said to the driver, Doug, as the race started. The front-runners started to 3 and then my eyes were drawn to the woman in blue silk running shorts and a loose white T-shirt. We knew we were already watching our "last runner." Her 4 were so crippled (残疾的) that it seemed almost impossible for her to be able to walk, let alone run a marathon. Doug and I watched in silence as she slowly moved forward. 5 , she was the only runner left in sight. Tears streamed down my face when I watched with respect 6 she pushed forward with great determination through the last miles. When the finish line came into sight, rubbish lay everywhere and the 7 crowds had long gone home. Yet, standing straight and ever so proud 8 a lone man. He was 9 one end of a ribbon (缎带) of crepe paper (皱纹纸) 10 to a post. She slowly crossed through, leaving both ends of the paper fluttering behind her. I do not know this woman's name, but that day she became part of my 11 - a part I often depend on. For her, it wasn't about 12 the other runners or winning a prize, but about 13 what she had set out to do, no matter 14 . When I think things are too difficult or I get those "I-just-can't-do-it," I think of the last runner. Then I realize how 15 the task before me really is. | ||||
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