11. All the apples ______ fell down from the tree were eaten up by the pigs.
A. which B. / C. that D. they
12. I can tell you ______ he told me last week.
A. all which B. all what C. that all D. all th
13. This is the biggest lab ______ we have ever built in our university.
A. which B. what C. that D. where
14. Is oxygen the only gas ______ helps fire burn?
A. that B. / C. which D. what
15. Air, ______ we breathe every day, is around us all the time.
A. that B. / C. which D. it
16. This is the museum ______ we saw an exhibition the other day.
A. that B. which C. where D. in that
17. This museum is ______ you visited the other day.
A. that B. which C. where D. the one
18. This is the museum ______ you saw the other day.
A. that B. where C. in which D. in that
19. It is the third time ______ late this month.
A. that you arrived B. when you arrived
C. that youve arrived D. when youve arrived
20. It was in 1969 ______ the American astronaut succeeded in landing on the moon.
A. that B. which C. in which D. when
答案：11-15 CDCAC 16-20 CDACA