【单选题】Echo-sounder is usually installed at the bottom of observation ship. The water line of ship is 15m. The sound speed is meanly 1500m/s. The time interval between receiving and launching sound wave is 3...
【简答题】Directions: Now, listen to the dialogue again to answer these questions. 1. What is good about a five-disc CD player? 2. Why does the customer like the direct access feature? 3. What kind of CD playe...
【简答题】1 一、根据句意或汉语提示填写单词。 1.Nothing is if you put your heart into it. 2.The math problem is so hard that of us can work it out. 3. travels much faster than sound. 4.How many study ( 组 )are there in your clas...
【简答题】一、根据句意或汉语提示填写单词。 1.Nothing is if you put your heart into it. 2.The math problem is so hard that of us can work it out. 3. travels much faster than sound. 4.How many study ( 组 )are there in your class?...