21. Understanding, sharing and commitment are ____________it takes to make love last.
A. that B. how C. where D. what
22. - Did you enjoy the party last Sunday
- Yes. That was the most wonderful time I ____________ .
A. have B. was having C. had ever had D. have ever had
23. The old saying "The early bird catches the worm" shows us the ________ of planning, working hard and trying constantly.
A. reality B. significance C. security D. recognition
24. Man has been using the earth’s resources more and more rapidly over the years, _______ some are almost gone.
A. of which B. of them C. for which D. for them
25. When an explosion happened in a chemical factory, the police ______the public not to panic.
A. referred to B. got across C. appealed to D. put forward
26. There are still many problems remaining to be solved ______we have a better earth to live on.
A. until B. once C. after D. before