(单选题)

According to the passage, the radar boat is used for ______

A.rescuing the swimmer from drowning when he is in danger

B.preventing him from being caught by the tide

C.equipping him for the dangerous crossing

D.giving him the right direction when a storm puts him off the course

参考答案：D

参考解析：

细节理解题。根据第三段最后一句“Boats equipped with radar now follow channel swimmers and help keep them on course with the tide changes.”可知，雷达船的作用就是在潮汐发生变化时，引领航道，故选D。

知识点：阅读理解四选一英语专业基础知识阅读理解教师招聘-小学英语