不能用more happy.
但是你可能见到这样的句子.
more Happy Holidays,
more happy love .
等.这里不是比较级,这里的HAPPY 是修饰后面的名词的.more 修饰后面的HAPPY+ 名词的.
例子：
He is __ when he is working
A.the happiest B.happiest C.more happy D.a few happy
答案是A.