21. Doctors are doing research to find out what happens physically when people _________ smoking.
A. quit B. decline C. depart D. reserve
22. I was ashamed _________ lied to my mother.
A. to be B. of having C. that D. of being
23. He risked __________ his job to see me off.
A. Losing B. to risk C. being lost D. Lost
