21. In washing this cloth, be sure to _______ the temperature of water.
A. allow for B. pay for C. account for D. answer for
22. One of the provinces _______ the union and formed a new country.
A. broke away from B. kept away from
C. did away with D. cut off
23. It is well known that Thomas Edison _______ the electric lamp.
A. invented B. discovered C. found D. developed
24. In order to get the exact result, the scientists made _______.
A. a lot tries B. to do experiments C. trial and error D. great try
