形容词形式：

　　以-n结尾的国家后面一般加-ese,【如中国和日本】；

　　多数西方国家后面加-n【如俄罗斯和美国】；

　　极少数国家是特殊形式【如法国France--French】.

　　至于人口,单数基本等于上述变法；

　　对于复数,则有【中日不变英法变,其他后边加-s】的说法：

　　这个表格应该能帮你解决难题.

　　┏国家┳┳┳┳┳┳┳┳人口单数┳┳┳┳┳┳┳┳复数┳┳┳┳┳┳┳┳┳┓

　　┣China╋╋╋╋╋╋╋╋Chinese╋╋╋╋╋╋╋╋Chinese╋╋╋╋╋╋╋┫

　　┣Japan╋╋╋╋╋╋╋╋Japanese╋╋╋╋╋╋╋Japanese╋╋╋╋╋╋╋┫

　　┣╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋┫

　　┣England╋╋╋╋╋╋╋Englishman╋╋╋╋╋╋╋Englishmen╋╋╋╋╋┫

　　┣France╋╋╋╋╋╋╋Frenchman╋╋╋╋╋╋╋╋Frenchmen╋╋╋╋╋┫

　　┣╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋╋┫

　　┣America╋╋╋╋╋╋╋American╋╋╋╋╋╋╋╋╋Americans（注意-s）┫

　　┣Russia╋╋╋╋╋╋╋Russian╋╋╋╋╋╋╋╋╋Russians╋╋╋╋╋┫

　　┗…┻┻┻┻┻┻┻┻┻…┻┻┻┻┻┻┻┻┻┻┻…┻┻┻┻┻┻┻┻┻┻┛

　　————————明白了吧,我可累惨了@^@————————