乱立flag是说如果做了某事，会发生相应的事情，但是一旦这句话说了，事情都会和预期相反。发生的事自己不想看到的事情。
关于flag的例句：
1、旗;旗帜;(尤指)国旗 A flag is a piece of cloth which can be attached to a pole and which is used as a sign, signal, or symbol of something, especially of a particular country.
2、The Marines climbed to the roof of the embassy building to raise the American flag...
3、 A flag is a small piece of paper or cloth attached to a stick or pin which is sold on a flag day or used to mark a particular spot.
4、旗帜(新闻用语，代指某个国家、组织或其价值观、权力) Journalists sometimes refer to the flag of a particular country or organization as a way of referring to the country or organization itself and its values or power.
5、Joining John Whitaker will be his brother Michael also riding under the British flag...
约翰·惠特克将与他的兄弟迈克尔一起代表英国参加这场自行车赛。
6、松劲;泄气;疲乏 If you flag or if your spirits flag, you begin to lose enthusiasm or energy.
His enthusiasm was in no way flagging...
他的热情丝毫未减。