题目

Do you have any hobbies? Do you know the hobbies of some famous people? Here are some examples:Mark TwainHe was a famous America writer and loved telling funny stories and playing jokes with others. He said his stories could make anyone laugh.Bill GatesThe founder of Microsoft likes playing I-go and ping-pong. He enjoys playing bridge, too. He often plays bridge with his friends.Liu XiangThe famous athlete likes singing songs besides doing sports. He can sing songs as well as professional singer. Can you tell some other famous people who have different hobbies?【1】What’s Mark Twain’s h已知集合.（1）证明：若，则，；（2）证明：若，则，并由此证明中的元素若满足，则；（3）设，试求满足的所有的可能值.