Many experts stick to the view __teacher development is _the key to quality education lies．

　 A．which; where　 　　　　　　 　　　　　　　 B．which; in which

　 C．that; where　 　　　　　　　 　　　　　　　 D．that; in which

China is one of the largest countries in the world,         9.6 million square (平方)kilometers.

 A. to cover                B. covered               C. covers                D. covering

Water ________ (存在) in three forms, which are liquid, gas and solid.

--We don’t know who stole the book. What’s your opinion?

--Jack is considered _______ it.

A. having done　　 B. to have done　　 C. doing　　 D. to do

—What do you think of teacher ,Bob？

—I find it fun and challenging. It is a job ___ you are doing something serious but interesting .

A. where　 　　　 B. which　　 　 C. when　　 　　D. that