题目

This is the first time the students ______ to Hyde Park.A. have been visited B. have visitedC. have gone D. are being gone 答案：【答案】C【解析】考查时态。句意：这是学生们第一次去海德公园。在this/it is the first time +从句的结构中，从句用现在完成时，故C项正确。由于visit是及物动词，其后直接接宾语，故排除B。 的平方根是     ．