Mar Levine, scientist at University of Pennsylvania, US, has found that competitive eater

Mar Levine, scientist at University of Pennsylvania, US, has found that competitive eaters have stomachs that can expand like balloon.
A. a; a
B. a; the
C. a; /
D. the; a

(答案→)A. a; aB. a; theC. a; /D. the; a解析：本题考查冠词。第一空a scientist at University of Pennsylvania表示泛指一位宾夕法尼亚大学的一位科学家；第二空a balloon仍然表示泛指气球。句意：Mar Levine，一位美国宾夕法尼亚大学的一位科学家，已经发现胜过他人的食客有能够像气球膨胀的胃。

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