21. How can Linda _____ from her illness in this room when it’s so dirty and cold? It will only make her worse.
A. escape B. recover C. separate D. graduate
22. —Did he break it accidentally?
—No, ______ .
A. by himself B. by chance C. on purpose D. by mistake
23．On Christmas Eve, we put up some balloons to ______ the atmosphere of the festival.
A. make for B. add up C. add to D. join in
