21. At the end of the cross-talk, ______ audience present in the hall burst into _____ laughter.

   A. an ; the          B. the ; a          C. an ; /           D. the; /

22. My chest _______ when I make a deep breath, doctor.

A. harms           B. wounds          C. hurts           D. injures

23. Travelling has really helped to broaden our ___________, which makes us wiser.

   A. differences       B. horizons         C. shortcomings      D. hardships