生日快乐的英文为：happy birthday
例句：
1.蛋糕上裱了“生日快乐”的字样。
The cake had'Happy Birthday'piped on it.
2.我祝她生日快乐。
I wished her a happy birthday.
We all crowded into her office to sing'Happy Birthday'.
4.妈妈，生日快乐！
Happy Birthday,Mum.
5.生日快乐，亲爱的。
Happy birthday,sweetheart.
6.生日快乐！
Happy Birthday!
7.祝您生日快乐！
Happy birthday to you!
8.他在蛋糕上镶上了“生日快乐”的字样。
He piped"happy birthday"on the cake.
9.全班学生一起对着老师唱起了《生日快乐》歌。
The whole class all joined together to sing happy birthday to the teacher.
10.全年生日快乐！
Happy Birthday All Year!
补充：
birthday party生日聚会
birthday cake生日蛋糕
birthday card生日贺卡
birthday
n.生日，诞辰；诞生的日子
happy
adj.幸福的；高兴的；巧妙的
n.(Happy)人名
