题目

—Hainan ________ its blue sky and fresh air.   —So it is. That’s why more and more visitors spend their holidays here. A. is weak in B. is famous for          C. is used to 答案：B小刘会在每周的一、二、三中随机一天去图书馆，小关会每周的二、三、四中随机一天去图书馆，小张会在每周的二、三中随机一天去图书馆．（1）求一周内三人同一天去图书馆的概率；（2）求一周内三人刚好在连续三天去图书馆的概率．