21. The bus stops regularly to _____ and pick up passengers.
A. set up B. set off C. set out D. set down
22. The police _____ the driver to stop the car immediately, because it was running too fast in the street.
A. begged B. wished C. commanded D. requested
23. —Why is she so ______about the boy’s disappearance?
—Oh, you know, she is the mother.
A. disappointed B. concerned C. excited D. interested
