We can catch      sight of millions of stars in      space.

   A. /, the       B. the, /          C. /,  /              D. a , the

       ______ life began on earth is one of the biggest puzzles that scientist found hard ______.

A. How; solving                                 B. When; to be solved

C. How; to solve                                D. Which; to solve

27. This cake is very sweet. You ______ a lot of sugar in it.

A. should put         B. might put          C. could have put          D. must have put

I still remember the sitting-room _______ my mother and I used to sit in the evening．

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

Henry set up a club for football fans, ________ he invited all his friends．

A．for whom    B．to whom   C．to which         D．from which

American women usually identify their best friend as someone _______ they can talk frequently．

       A．who        B．as      C．about which          D．with whom

It is ______ he said to his father that made him very sad.

A. who                                  B. that                                  C. how                                  D. what