About _______ of the surface of the earth _______ covered with water.

  A. three quarter, is     B. three quarters, has    C. three quarters, is    D. three quarter, are

It has been estimated that the earth’s surface temperature has increased _____ sone quarter to three quarters of a degree since 1850. 
A. to     B. by      C. at     D. with 

About _______ of the surface of the earth _______ covered with water.

_____ of the world’s books and newspapers are written in English.

  　A. Three quarter             B. Three of quarters  

   C. Third fourths              D. Three fourths

It has been estimated(估计) that the earth's surface temperature has increased _____ sone quarter to three quarters of a degree since 1850.

A. to　　 B. by　　 C. at　　 D. with