We collect money in behalf of the homeless.
我们为无家可归的人筹钱。
I, on behalf of our class, welcome you warmly and sincerely.
我代表我们班级，真诚、热情地欢迎你。
They write letters of recommendation on behalf of students.
他们为学生写推荐信。
Don’t worry on my behalf.
别为我担心。