21. In the United States, there is always ______ flow of people to areas of ____country where more jobs can be found.
A. a; the B. the; a C. the; the D. a; a
22. The rise in consumer spending is an encouraging ______ that the economy may be recovering.
A. symptom B. solution C. subject D. sign
23. Arriving at a bus stop _____ the vehicle pulling away just a few minutes ago is quite annoying.
A. to find B. finding C. found D. to be finding
