问题
选择题
To test _____ danger of not enough sleep caused by playing computer games, scientists did _____ experiment. [ ]
A. a; /
B. a; the
C. the; an
D. /; an
答案
答案：C
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To test _____ danger of not enough sleep caused by playing computer games, scientists did _____ experiment. [ ]
A. a; /
B. a; the
C. the; an
D. /; an
答案：C