小明和小强下五子棋，两人决定同时各掷一枚硬币，两枚正面或两枚反面朝上，小明先出棋，否则小强先出棋．请回答以下问题．
（1）两枚正面都朝上的可能性是______．
（2）两枚反面都朝上的可能性是______．
（3）一枚正面朝上、一枚反面朝上的可能性是______．
（4）你认为这个规则公平吗？
因为“两人同时各掷一枚硬币一次”可能会出现：正正、反反、反正、正反4种结果，所以：
（1）两枚正面都朝上的可能性是：1÷4=
；1 4
（2）两枚反面都朝上的可能性是：1÷4=
；1 4
（3）一枚正面朝上、一枚反面朝上的可能性是：2÷4=
；1 2
（4）因为小明先出棋的可能性为：2÷4=12；小强先出棋的可能性为：2÷4=
；1 2
因为
=1 2
，所以这个规则公平．1 2
故答案为：
，1 4
，1 4
．1 2
Birthdays are strange things. The more you have, the more you try and pretend they don’t matter, and the more 小题1: . I’m not really sure why they think so. It’s true that you are getting older, but as 小题2: , “Who isn’t getting older every day?” The problem may be that a birthday reminds people of all the things 小题3: , but have not. I certainly understand that feeling, though I think 小题4: that I most want to do — a kind of personal re-ordering (重新排序) of the to-do list. What makes you depressed(郁闷) on your birthday is that you realize your re-ordered to-do list is exactly the same as it was last year. That makes you feel 小题5: , and not been anywhere. I have not had that experience this year. I look back at where I was last year and find things have changed since then. |