问题
不定项选择
| 不定项选择 |
| 火箭在大气中飞行时，它的头部跟空气摩擦发热，温度可达几千摄氏度，在火箭上涂一层特殊材料，这种材料在高温下熔化并且汽化，能起到防止烧坏火箭头部的作用，这是因为（ ） |
| A．熔化和汽化都放热 B．熔化和汽化都吸热 C．熔化吸热，汽化放热 D．熔化放热，汽化吸热 |
答案
答案：B
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| 不定项选择 |
| 火箭在大气中飞行时，它的头部跟空气摩擦发热，温度可达几千摄氏度，在火箭上涂一层特殊材料，这种材料在高温下熔化并且汽化，能起到防止烧坏火箭头部的作用，这是因为（ ） |
| A．熔化和汽化都放热 B．熔化和汽化都吸热 C．熔化吸热，汽化放热 D．熔化放热，汽化吸热 |
答案：B
| 完形填空。 | ||||
| My mother let go of me when I could not let go of her .In one last brave moment she was strong for me ,thus making me strong ,too. I was in the kitchen when 1 called and told me to make a quick decision .They could only hold a place for my 2 until the next morning. The thought of being 3 from my Alzheimer's stricken (早老性痴呆)mother when she needed me most 4 me .Dad died when I was a teenager ,Mom and I had 5 many hard times together .Mom taught me to laugh my way through bad experiences and sing through 6 days .But in recent years , except for extremely 7 moments of consciousness , she'd become lost in her own private world .I knew that Mom needed 8 nursing and medical care ,yet the possibility of a complete stranger coming to her at night ,when she would 9 around like a sleepwalking child ,filled me with a feeling of 10 . Two bitter days passed 11 we left for the nursing home .I hugged and kissed her with 12 tears, I'd always planned the best golden years for Mom in her old age ,but now I was saying 13 . Suddenly there was something shining in her 14 ,a look of recognition ."Stop crying now",she said firmly ,"Say goodbye and get going .Don't 15 about me ." I stood with 16 and stared into her face ."Mom!"I cried and reached out for her .But as quickly as my "real "Mom had appeared ,she 17 again into her world of a little child 18 ,at that very moment I realized the mother ,that familiar Mom who knew and understood ,who 19 and sang with me in hard times ,would always be there ,giving me 20 when I needed it most . | ||||
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