21.－What's the matter ＿＿ you?
－I have pains in the eyes.
A.for B.of C.on D. with
22. You won't have any problems ＿＿ place.
A.find B.found C.finding D.to find
23. Sam looks so sad. Let＇s go and ＿＿.
A.cheer up her B. cheer her up C. cheer up him D. 
cheer him up
24. Could you please help me carry this heavy box?
－____________.
