题目

已知某广播电视台的频率是20000 kHz，求此电台发出的电磁波的波长是多少？是属于中波还是短波？（国际规定：中波波长为3000m~200m，短波波长为200m~10m） 答案：根据公式c=λf，故该电磁波的波长： λ=15m短波1.Hearing what the boy said, we felt _______________( confuse) and looked at each other. 2._______________( compare) with that old computer, the new one is smaller but works faster. 3.Jack, ______________brother works in our company, is going to give us a talk on how to learn English. 4.One of the __________________( require) for a fire is that the material be heated to its burning temperature. 5.His speech is very important, ______________it is short. 6.The public were shocked when they heard the president ___________ ( murder) 7.The Chinese people are determined _________________( fight) all the difficulties to realize the Chinese dream. 8.There were lively New Year _______________________( celebrate) all over the town. 9.We had to be patient because it would be some time ___________we got the full results. 10.When I called his name, he rose ________his feet and smiled at me. 11.They try to protect __________________( danger) animals, such as Tibetan antelope. 12.I ________________( hope) that our volleyball team could win, but it didn’t. 13.This is the village _____________we visited last year. 14.____________ was Tom who helped the disabled girl to go across the street. 15.In the last few years, China has made great achievements in environmental ______________________( protect).