21. I am _____ first cloned monkey and I was born at _____ research center in the USA.

   A. the; a              B. an; the             C. /; a              D. the; the

22. Football is very important to me, but _____ is our friendship.

   A. as                 B. so                C. also              D. too

23. When _____ who is their best friends, the boys usually hesitate before responding.

   A. asking             B. asked              C. ask              D. to ask