题干

关于机械波,下列说法正确的是(   )

A:在传播过程中能传递能量

B:频率由波源决定

C:机械波是介质随着波一起迁移的运动

D:能在真空中传播

上一题 下一题 0.0难度 选择题 更新时间:2018-10-11 11:10:41

答案(点此获取答案解析)

A,B,D

同类题2

根据短文理解,选择正确答案。

Marco Polo

    Marco Polo was born in Italy in 1254. A traveller and businessman, he was one of the first Europeans to travel across Asia and into China. His journey lasted 24 years.

    He set out, aged 17, with his father Nicolo and his uncle Maffeo on their great journey to China. They sailed south from Venice, Italy and stopped off in the Middle East. They ofen carried on overland to Persia (now Iran), through the Pamir Mountains and the Gobi Desert before they got to Beijing, China.At that time, China was more advanced than Europe. They already had paper, so large numbers of books were available. They also used paper money in many parts of the country.

    After he got back to Italy, Marco Polo talked about his experiences in China, and he wrote a book describing the riches of Asia. His book was the first western record of porcelain(瓷器), coal, gunpowder, printing and silk.Unfortunately, not many people believed Polo's stories and he became known as “the man of a million lies”. He died in 1324.

Jacques Cousteau

    Jacques Cousteau was a French undersea explorer, environmentalist and inventor. He was born in France in 1910. When he was young, he was attracted by the sea, machines and filmmaking. In the French navy, Cousteau began exploring underwater and worked on a special breathing machine which allowed divers to stay underwater for several hours. This gave them time to really look around under the ocean. In 1948, Cousteau began travelling the world's oceans in his research ship Calypso.Cousteau produced many films and books about his underwater experiences, including the TV series The Underwater World of Jacques Cousteau, which introduced the public to the world of sharks, whales, dolphins and treasure.

    Cousteau started the Cousteau Society to protect ocean life. In 1989, he received a great honour: he was made a member of the French Academy. Finally, after a long and varied life, Cousteau died on 25th June, 1997.