20.Machinery ______ rapidly if it is not taken care of .
A. devastates
B. destroys
C. dedicates
D. deteriorates
21.Some very important issues were ______ all his attention.
A. taking up
B. taking off
C. taking out
D. taking in
22.Knowledge then is the _____ condition of expansion of mind.
A. indigestible
B. indispensable
C. indissoluble
D. indisputable
23._______ composers such as Mozart, who was treated as an employee by those who commissioned him, Beethoven enjoyed equal social status with his employers.
A. Because
B. There were
C. Unlike
D. Having been
24.Greater efforts to increase wheat production must be made if bread shortages _______avoided.
A. will be
B. can be
C. are to be
D. were to be
25.Air ______ of a combination of nitrogen and oxygen.
A. composes
B. comprises
C. forms
D. consists
