The author states that during dream sleep, the animal sleeps

• A、without moving
  
  

• B、shallowly
  
  

• C、intermittently
  
  

• D、on its side
  
  

George Strong was the best engineer in Henry Manley's company.

• A、True
  
  

• B、False
  
  

• C、Not Given
  
  

Task 1

16. Paragraph     ①     

17. Paragraph     ②     

18. Paragraph     ③     

19. Paragraph     ④     

20. Paragraph     ⑤     

A. Lightening Causes Puzzles to People

B. Types of Lightning

C. Causes of Lightning

D. Differences Between Thunder and Thunderstorm

E. Frequencies of Thunderstorms Occurring in the World and the U. S.

F. Shock Waves as Thunder