21. I woke up with _____ bad headache, yet by _____ evening the pain had gone.
A. the; the B. the ; an C. a; the D. a; an
22. Walking alone in the dark, the boy whistled to _____ his courage.
A. pick up B. keep up C. set up D. give up
23. She pretended ______ me when I passed by, which made me puzzled.
A. not to see B. not seeing C. to not see D. having not seen
