In review off 44 studies, American researchers found that men and women who ate six key foods daily cut the risk of heart disease by 76%.
A. a; the
B. the; a
C. a; 不填
D. 不填; a
网友回答
A. a; the
B. the; a
(答案→)C. a; 不填
D. 不填; a
解析：第一空填不定冠词，表示“一次”；第二空不填冠词（或填零冠词)，因为此处是表泛指。