As discovered by expedition scientists, Antarctica has not always been so cold as it is today, so has the Arctic.

• A、True
  
  

• B、False 
  
  

• C、Not Given
  
  

假如你是Jerry,你的好朋友John 考上了耶鲁大学，请根据以下内容要点给他写一封150 词左右的英文祝贺信：

Main content:

1) congratulations;

2) the differences between college life and high school life;

3) your suggestions on a good college life.

Task 2

21. In the twentieth century, soot          

22. If snow and ice covered areas begin melting,           

23. A soot forcing is unusually effective, which          

24. Hansen cautioned that greenhouse gases          

25. Warming in the Northern Hemisphere was large in at middle and high latitudes.           

A. produces much more global warming than a carbon-dioxide forcing of the same magnitude

B. contributed to 25 percent of observed global warming

C. winter and spring

D. the warming effects increase

E. still surpass soot in warming the world's climate during the last century

F. can be seen mostly in the Northern Hemisphere