你好！~am是be 动词 ，be动词后加形容词。glad是形容词，gladly是副词。所以选glad。I am glad to see you 见到你我很高兴，等同于nice to see you暑假愉快~~
glad 是形容词，gladly是副词be 后加形容词
I am glad to see you
i am glad to see you
glad
