题型:填空题 已知空气中的声速V空 =340m/s,有一声波在空气中的波长为λ空 =1m,则该声波的频率为__ __HZ。该声波在水中传播时(已知V水=1450m/s)的波长为 m。若已知该声波在铁轨中传播时的波长为14.4m,则可计算出铁轨中的声速为____ ____m/s。 查看答案
题型:填空题 Get in touch with them, for they will be anxious _____ news of your arrival. A.atB.forC.aboutD.to 查看答案
题型:填空题 Though he didn’t agree with us at first,we soon ________ him to our way of thinking.[ ]A.converted B.transferredC.modified D.exchanged 查看答案