21. A low-carbon lifestyle is of great benefit to improve_____ world environment. Nothing can be enjoyed from it until you have____ deep understanding of it, though.
A. a; the B. /; a C. the; / D. the; a
22. —Why do you want to work for our company?
—This is the job that I ______for.
A. looked B. am to look C. had looked D. have been looking
