The British Union flag is more often called Union Flag or Union Jack.With a 1:2 proportion of width to length,the Union Jack has a design of The Cross of Saint Andrew counterchanged with the Cross of Saint Patrick,over all the Cross of Saint George.Adopted in 1801,the flag is used as the national flag and naval ensign and retains an official or semiofficial status in some Commonwealth Realms.
30个词绝对不够的,你能用30个词描述中国国旗吗?何况英语单词肯定比汉字多.