Which of the following is true of the fossil deposits discussed in the passage?

• A、They include examples of newly discovered species.
  
  

• B、They contain large numbers of well-preserved specimens
  
  

• C、They are older than fossils found in other places.
  
  

• D、They have been analyzed more carefully than other fossils.
  
  

Why does the author mention the specimen preserved in the birth canal?

• A、To illustrate that the embryo fossils are quite advanced in their development.
  
  

• B、To explain why the fossils are well preserved
  
  

• C、To explain why the fossils are well preserved
  
  

• D、To prove that ichthyosaurs are marine animals
  
  

Task 2

21.For as long as three months of a year, the sun_________on the ice-covered land of Alaska

22.According to statistics,_________of the total area of Alaska has been used for farming,

23.Alaska was originally part of Russia, but was bought_________

24.Gold did not bring to Alaska as much wealth_________

25._________has become Alaska's single important resource.

A. as fish does

B. oil

C. by the United States in the 19th century

D. shines day and night

E. only a very small percentage

F. a limited amount of the gold found there