下列关于声音的说法正确的是
A．声波是一种电磁波
B．戴上耳塞是在人耳处减弱噪声
C．“闻其声而知其人”是根据响度来判断的
D．调节MP3音量是改变了音调
B。
声波不是电磁波，声波是由物体的振动产生的，电磁波是由变化的电流产生的，故A不对；B中戴上耳塞是在人耳处减弱噪声，B是正确的；C中“闻其声而知其人”是根据声音的音色来判断的，C不对；D中调节MP3音量是改变了响度，故D也不对。
| 完形填空。 | |||
| The True Story of Treasure Island It was always thought that Treasure Island was the product of Robert Louis Stevenson's imagination. 1 , recent research has found the true story of this exciting work. Stevenson, a Scotsman, had lived 2 for many years. In 1881 he returned to Scotland for a 3 . With him were his American wife and his son 4 . Each morning Stevenson would take them out for a long 5 over the hills. They had been 6 this for several days before the weather suddenly took a turn fro the worse. Kept indoors by the heavy rain, Lloyd felt the days 7 . To keep the boy happy, Robert asked the boy to do some 8 . One morning, the boy came to Robert with a beautiful map of an island. Robert 9 that the boy had drawn a large cross in the middle of 10 ."What is that?" he asked. " That's the 11 treasure ,"said the boy. Robert suddenly 12 something of an adventure story in the boy's 13 .While the rain was pouring, Robert sat down by the fire to write a story. He would make the 14 a twelve-year-old boy, just like Lloyd. But who would be the pirate (海盗) ? Robert had a good friend named Henley, who walked around with the 15 of a wooden leg. Robert had always wanted to 16 such a man in a story . 17 Long John Silver, the pirate with a wooden leg, was 18 . So, thanks to a 19 September in Scotland, a friend with a wooden leg, and the imagination of a twelve-year-old boy, we have one of the greatest 20 stories in the English language. | |||
| ( )1. A. However ( )2. A. alone ( )3. A. meeting ( )4. A. Lloyd ( )5. A. talk ( )6. A. attempting ( )7. A. quiet ( )8. A. cleaning ( )9. A doubted ( )10. A the sea ( )11. A. forgotten ( )12. A. saw ( )13. A. book ( )14. A. star ( )15. A. help ( )16. A. praise ( )17. A. Yet ( )18. A. read ( )19. A. rainy ( )20. A. news | B. Therefore B. next door B. story B. Robert B. rest B. missing B. dull B. writing B. noticed B. the house B. buried B. drew B. reply B. hero B. problem B. produce B. Also B. born B. sunny B. love | C. Besides C. at home C. holiday C. Henley C. walk C. planning C. busy C. drawing C. decided C. Scotland C. discovered C. made C. picture C. writer C. use C. include C. But C. hired C. cool C. real-life | D. Finally D. abroad D. job D. John D. game D. enjoying D. cold D. exercising D. recognized D. the island D. unexpected D. learned D. mind D. child D. bottom D. accept D. Thus D. written D. windy D. adventure |