质量为500克的铁壶中放有3千克水,把这一壶20оC的水烧开(一标准大气压),问:
(1)需要吸收多少热量.
(2)若用效率为40%的炉子加热,烧开这壶水需燃烧多少克烟煤?(铁的比热容为0.46×103焦/(千克•℃),无烟煤的燃烧值为3.4×107焦/千克)
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男性,12岁。1个月前进食不慎,自觉食物呛入气管,此后出现频繁咳嗽,咳黄脓痰。曾发热,胸部平片:未见明显异常()。
A.水泡音
B.哮鸣音
C.胸膜摩擦音
D.Velcro啰音(捻发音)
E.鼾音
联合国在1992年的第47届联合国大会举行了老龄问题特别会议,讨论通过了《老龄问题宣言》,宣言规定哪一年定为国际老人年
A.1996
B.1997
C.1998
D.1999
E.2000
患者,男,10岁,颏部发育差,唇前突闭合不全,面下1/3高度偏大,有咬下唇习惯,覆盖8mm,磨牙完全远中关系,前牙深覆
目前矫治首选下列哪项方案()
A.常规固定正畸治疗
B.骨骼的矫形治疗
C.正颌外科
D.生长停止后口腔正畸与正颌外科
E.以上都不是
Night after night, my mother came to my bed, even long after my childhood years. She would 21 down and push my long hair out of the way, and then kiss my forehead. I don’t remember when it first started 22 me-her hands pushing my hair that way, for they felt work-worn and rough 23 my young skin. Finally , one night, I shouted out at her, “Don’t do that any more-your hands are too rough!” she made no 24 and left quietly. But never again did my mother do it with that familiar expression of her 25 . With the passing years, my 26 returned to that night time after time. By then I 27 my mother’s hands and her goodnight kiss. Sometimes the incident seemed very 28 , sometimes far away, but always it was 29 in the back of my mind. The years have passed, and I’m not a little girl any more. Mom is in her seventies, and those hands I once 30 to be so rough are still doing things for me and my family. Now, Mom no longer has Dad and lives 31 . One night on Thanksgiving Eve, I found myself 32 to her house to spend the night with her. As I slept in the bedroom of my youth, a familiar hand hesitantly ran across my face to 33 the hair from my forehead. Then a 34 , ever so gently , touched my forehead. I burst into tears. In my memory, thousands of times, I 35 the night my young voice complained. Catching Mom’s hand in hand, I told her how 36 I was for that night. I thought she’d remember 37 I did. But Mom didn’t know what I was talking about. She had already forgotten and 38 long ago. That night, I fell asleep with a new 39 for my gentle mother and her caring hands. And the guilt that I had carried around for so long was 40 to be found.
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综合性货场按作业量大小可分为()。
A、特大型货场
B、大型货场
C、中型货场
D、小型货场
E、货区