21. the play had been on for 10 minutes but i was still unable to find a seat_____. a. to sit b. to sit on c. sit d. sit on 22. _______many times , they succeeded _____ the experiment. a. having tried, in doing b. tried , in doing c. having tried, to do d. tried, to do 23. he fell off his bike and hurt his back. _____, he will have to stay in bed for long . a. after all b. in any case c. as a result d. in particular 24. helen had to shout ____above the sound of the music. a. making herself heard b. to make herself hear c. making herself hear d. to make herself heard
