22. Although absolute zero cannot actually be reached, approximations of less than 0.001 degrees Celsius above absolute zero have been created in the laboratory.
选B是错误的.要选D
怎么改?
8. Small to medium-sized marsh birds similar in body shape to cranes, rails are found throughout the world, except in the Polar Regions.选D错..要选B. 怎么改?
20. It is said that no potential frontier has so fired the imagination or challenged the ingenuity of humankind as has space.
选A错
要选B. why? | 
