第6部分：完形填空(第51～65题，每题1分，共15分)
下面的短文有15处空白，请根据短文内容为每处空白确定1个最佳选项。
51.
A. Consider
B. Considering
C. Considered
D. Having considered
52.
A. totals
B. money
C. sums
D. dollars
53.
A. to
B. for
C. by
D. /
54.
A. various
B. variable
C. varied
D. variant
55.
A. from
B. in
C. out of
D. by
56.
A. has learned
B. has been learned
C. is learned
D. can learn
57.
A. is
B. are
C. has
D. was
58.
A. effective
B. efficient
C. more effective
D. effect
59.
A. economic
B. economical
C. economies
D. economy
60.
A. improve
B. improving
C. improved
D. being improved
61.
A. as
B. unless
C. although
D. though
62.
A. that
B. it
C. which
D. /
63.
A. observe
B. observes
C. observing
D. to observe
64.
A. Increasing
B. Increased
C. Increasingly
D. To increase
65.
A. which
B. for which
C. among which
D. of which