如果说某人 fly the flag 那么就表示摇旗呐喊，支持自己的国家（或团体）尤其是在国外。

例句

I'll be flying the flag for the company when I speak at that big conference in India next week.

Lang Lang flies the flag for China when he plays on the international stage.

请注意

注意另一个单词 flagging 表示体力或能量的衰减，没力气了。

例句

By the 40th kilometre the marathon runner was really flagging. It looked like she wouldn't complete the race.