21. There are_____ large number of people there, so we soon lost____ sight of him.
A. the; × B.×; the C. a; × D. a; the
22. To keep healthy, Mr. Smith_______ cycling as a regular form of exercise after he retired.
A. took up B. put up C. gave up D. made up
23．We’d like to arrive half an hour early________ we can have time for a good rest.
A. in case B. so as to C. as soon as D. so that
