请将下面这段话翻译成英文：

　　爱国精神(patriotism)是指热爱祖国和愿意为之牺牲，是我们评价一个人的品德和行为的必要标准。虽然，中国人的爱国精神在不同的历史时期有着不同的具体内容和特点，但一直都和热爱祖国、热爱家乡、热爱人民联系在一起。爱国精神是一种伟大的凝聚力(cohesive force)。当国家被人侵或者出现分裂的局面时，人们总能在爱国精神的影响下，从国家和民族的大义出发，维护国家团结和统一。同时,爱国精神也是催人奋进的强大精神力量，鼓舞着人们为祖国和人民建功立业。

　　参考翻译

　　Patriotism,which refers to the love of one's country and the willingness to sacrifice for it,is a necessary criterion for us to evaluate one's virtue and conduct.Although Chinese people's patriotism has different contents and features in different historical periods,it's always associated with the love for the country,hometown,and people. Patriotism is a great cohesive force.When the country is invaded or split,people can always defend national unity and unification from the overall interests of the state and thejusticial cause of the Chinese nation under the influence of patriotism. Meanwhile,patriotism is a strong and inspiring mental power that encourages people to render remarkable services and establish a distinguished career for the people and the country.