The astronaut did many experiments in the spaceship, ______ much help for knowing space.

A. which we think it is                                             B. which we think are of

C. of which we think are                                         D. I think which is of

The astronaut did many experiments in the spaceship,__________________much help for knowing space.

A. which we think it is    B. which we think are of 

C. of which we think is    D. I think which is of

The astronaut did many experiments in the spaceship,__________________much help for knowing space.

A. which we think it is    B. which we think are of 

C. of which we think is    D. I think which is of

The astronaut did many experiments in the spaceship,__________________much help for knowing space.

A. which we think it is    B. which we think are of 

C. of which we think is   D. I think which is of

The astronaut did many experiments in the spaceship, ________ much help for knowing space．

1. A.
   which we think it is
2. B.
   which we think are of
3. C.
   of which we think is
4. D.
   I think which is of