21. People are living in ___ world where mouse clicks rule our life, so online searches have become _____ must.
A. the; / B. /; a C. a; a D. a; the
22. He narrowly missed being seriously hurt, if not ________, by the explosion.
A. killed B. being killed C. be killed D. to be killed
23. Most of the roads were covered with thick snow, ____ made our journey more difficult.
A. one B. it C. which D. that
