问题
单项选择题
在用盐水作载冷剂的制冷系统中，要求盐水的凝固点温度应低于制冷剂的蒸发温度（）。
A、2～3℃
B、10～15℃
C、6～8℃
D、1～2℃
答案
参考答案：C
搜题请搜索小程序“爱下问搜题”
在用盐水作载冷剂的制冷系统中，要求盐水的凝固点温度应低于制冷剂的蒸发温度（）。
A、2～3℃
B、10～15℃
C、6～8℃
D、1～2℃
参考答案：C
（1）某学生用螺旋测微器在测定某一金属丝时，测得的结果如下图左所示，则该金属丝的直径d=______mm．另一位学生用游标尺上标有20等分刻度的游标卡尺测一工件的长度，测得的结果如图b所示，则该工件的长度L=______cm．
（2）某同学在研究长直导线周围的磁场时，为增大电流，用多根导线捆在一起代替长直导线，不断改变多根导线中的总电流I和测试点与直导线的距离r，测得下表所列数据：
I/A r/m B/T | 5.0 | 10.0 | 20.0 |
| 0.020 | 4.98×10-5 | 10.32×10-5 | 19.73×10-5 |
| 0.040 | 2.54×10-5 | 5.12×10-5 | 9.95×10-5 |
| 0.060 | 1.63×10-5 | 3.28×10-5 | 6.72×10-5 |
| 0.080 | 1.28×10-5 | 2.57×10-5 | 5.03×10-5 |
During the last fifteen years of my mother's life she suffered with Alzheimer's disease. Until then she had been a bright, __51__ woman deeply interested and involved in the world around her. I would go home to visit her in Virginia and she would look at me in a(an) __52__ way and ask, "Who are you?" I would answer, "I'm your son." "Where do you live?" She would ask. "In California," I would tell her. "Isn't that interesting," she would say, "I have a son in California." She seemed __53__ forgetful and confused at the beginning of the disease, __54__ later on she would go __55__periods of intense anxiety. She would pace through the house she had lived in most of her life __56__ uneasily that she wanted to go home. Or she would leave home and wander away if she were __57__ for a short time. Hoping to please her and put her mind __58__ I would take her for a drive, visiting sites where she had lived as a __59__. In the yard of the hillside house in Shipman I sat in the car and admired the view of the old oaks and long green lawn. I __60__ my mother there as a little girl playing with the pet lamb she had been so fond of. I looked to her for some __61__. She shook her head and said, "I want to go home." Over the years I have decided that what my mother was calling home was not a __62__, but a time. I suspect it was a time when she was much __63__, when her children were still underfoot, when her husband was still vigorous and attentive. Watching my mother's suffering set me wondering __64__ I would have in mind if someday I couldn't find __65__ and wanted to go there. In this family we tend to be long-lived and we grow fuzzy (糊涂的) minded as the years go by. At eighty I have already noticed some __66__ symptoms. My doctor says the forgetfulness is only __67__ and that it comes with age. Still the fear of Alzheimer's is haunting there. Someday __68__ and when I become even more __69__ minded than I am now, unable to drive and unable to tell you where "home" is, my dear son, I expect I will ask you to take me home, I know you will do your best to find the place I need to be. I leave these notes for your __70__.
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