91. The professor's ______ lecture on American history served more to confuse the students than to clarify the difficult material.
A. perspicacious
B. exhaustive
C. cogent
D. scintillating
E. disjointed

92. Since the foreign correspondent was accustomed to completing his assignments under ______ conditions, the commotion of the subway, at rush hour presented no ______ his creativity.
A. squalid, boon for
B. tranquil, obstruction to
C. tumultuous, impediment to
D. destructive, demonstration of
E. flagrant, benefit to

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