21. Results from a recent research indicate that ______ daydreaming is ______ means of relaxation.
A. the; a B. 不填; the C. a; the D. 不填; a
22. ________, more than 200 houses and buildings are heated by solar energy, not to mention the big cities.
A. In the alone small town B. In the small town alone
C. Alone in the small town D. In the small alone town
23. ---Ring me at 7 a.m.? ---No, not that early! I _________.
A. sleep B. will sleep C. am sleeping D. will be sleeping
24. Scientists generally agree that Earth’s climate will warm up over the next 50 to 100 years _________ it has warmed in the 20,000 years since the Ice Age.
A. as long as B. as much as C. as soon as D. as well as
