51．
A．course
B．cause
C．court
D．reason
52．
A．on
B．up
C．in
D．down
53．
A．cancer
B．health
C．disease
D．man
54．
A．dance
B．turn
C．take
D．play
55．
A．while
B．if
C．unless
D．since
56．
A．percent
B．countries
C．people
D．number
57．
A．at
B．in
C．of
D．for
58．
A．risk
B．degree
C．presence
D．place
59．
A．reduced
B．increased
C．mysterious
D．seen
60．
A．whether
B．why
C．that
D．if
61．
A．still
B．also
C．although
D．however
62．
A．decisions
B．questions
C．answers
D．needs
63．
A．lowest
B．enough
C．daily
D．perfect
64．
A．home
B．most
C．least
D．best
65．
A．causing
B．including
C．illustration
D．defining