1. ---People, especially teens, think it_____ great fun to surf on _____ Internet.
--- I agree with you.
A. a; the B. a; / C. /; the D./ ; /
2.---Look! _________ clean the park looks !
---Yes. I’m sure someone __________ it up.
A. What , has cleaned B. How , has cleaned
C. What , cleaned D．How ,cleaned
3. Scientists think life on Mars will be better than ________on Earth ______ many ways.
A. the one, on B. that, on C. that, in D. the one, in
