_____, the population of China is the largest in the world.

A. It is known that 　 　　 B. As is well known

C. Which is well known 　 D. We all know that

_____, the population of China is the largest in the world.

1. A.
   It is known that
2. B.
   As is well known
3. C.
   Which is well known
4. D.
   We all know that

_________, the population of China is the largest in the world.

A. It is well known that　　　　　　　　　　 B. As is well known

C. Which is well known　　　　　　　　　　 D. We all know

             the population of China is the largest in the world.

A. It is well known that                                         B. As is well known  

C. Which is well known                                         D. That is well known