【题目】A survey of the opinions of experts that three hours of outdoor exercise a week good for one’s health.
A. show; are
B. shows; is
C. show; is
D. shows; are
在线课程【答案】B
【解析】由a survey可知第一个空用shows, 首先排除A、C两项；第二个空前的时间three hours of outdoor exercise a week表示抽象概念, 看作单数, 故其谓语动词用单数形式。