题目内容
测量双绞线参数ACR时,测得的分贝值越大,说明衰减串扰比越小。
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线缆传输的衰减量会随着长度和频率的增加而增大。
衰减时传输所造成的信号损耗,以分贝(dB)表示。
串扰是两条信号的耦合,信号线之间的互感和互容引起线上的扰乱。
I. Blank filling: Confusable words (近义词辨析)(Directions:) Fill in the blanks with the words. Change the form where necessary (必要时改变单词的形式，如时态、单复数).Group 1ban, forbid, prohibit1. In some countries the sale of alcoholic beverages is _____. 在一些国家禁止出售含酒精的饮料。2. The treaty ____ all nuclear tests. 该条约禁止一切核试验。3. He _____ his children sweets because he didn’t want their teeth to be ruined. 他不许孩子们吃糖果，因为他不希望他们的牙齿蛀坏。Group 2invent, discover4. The planet Pluto was ______ in 1930. 冥王星是在1930年被发现的。5. Alexander Graham Bell ______ the telephone. 亚历山大•格雷厄姆•贝尔发明了电话。Group 3descend, fall, drop6. The rain was still __________ from the trees.7. On turning the corner, we saw that the road ______ steeply.8. Large masses of rock are constantly ______ into the sea.9. The hawk (鹰) ______ in a vertical stoop on its quarry (猎物).Group 4conquer, beat, defeat10. She ______ her brother at tennis. 在网球上，她打败了她弟弟。11. The Romans _____ parts of Britain in the first century B. C. 公元前一世纪罗马人曾占领了英国的部分领土。12. He was _____ by 165 votes against 132. 他以132票对165 票落选了。Group 5source, origin13. They had to find a new ______ of income. 他们不得不寻找新的收入来源。14. There are a number of words in the English language which were French in __________.15. Where is the _______of the River Thames?16. They had to find a new _________ of income.17. This practice owes its _________ to the Chinese.
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