21．Pay_____ attention to road signs while driving in_____ foreign countries.
A. /; / B. an; / C. a; / D. the; /
22．Mrs. Green wants to buy that kind of cloth because the cloth_____ very well.
A. washes B. washed C. is washed D. was washed
23．Was it in front of the market_____ the road accident happened yesterday?
A. will B. why C. which D. that
