21. The story shows that _______ knowledge of _______ first aid can make ______ real difference.
A. the; the; / B. a; /; a C. /; the; a D. a; /; /
22. We have phoned her several times, but unfortunately she is still out of _________.
A. order B. control C. sight D. reach
23. —Did you tell Rose about the test?
—Oh, no, I forgot. I call her now.
A. will B. can C. should D. might
