Some researchers are finding that daydreaming may be important to mental health .Daydreami

问题补充：

Some researchers are finding that daydreaming may be important to mental health .Daydreaming ,they say, is good means of relaxation.

A. the; /

B. /; the

C. /; /

D. /; a

答案：

A. the; /

B. /; the

C. /; /

(答案→)D. /; a

解析：考查冠词。第一空的mental health精神健康是一个抽象名词，单独使用，不要冠词；第二空用a泛指一种放松的方式。句意：一些研究人员分析白日梦对于精神健康很重要。他们说白日梦是一种很好的放松的方式。故D正确。