fly the flag

(of a ship) be registered in a particular country and sail under its flag

（船）在某国注册并挂该国国旗行驶

keep the flag flying

represent one's country or organization, especially when abroad

（尤指在海外时）代表自己的国家（或组织）

British products are keeping the flag flying for the home country.

英国产品代表着英国形象。

put the flags (或 flag) out

celebrate

庆祝，庆贺

temperatures are increasing again—that's why we're putting out the flags.

气温又一次在回升——所以我们要庆祝。

show the flag

(of a naval vessel) make an official visit to a foreign port, especially as a show of strength

（尤指海军舰艇为展示实力而）正式访问外国港口

wrap oneself in the flag

(chiefly N. Amer.)make an excessive show of one's patriotism, especially for political ends

(主北美)（尤指为政治目的而）过分表现爱国热情