1.Agree on 一致同意
Me and my friend both agree on the fact that we should not date anymore considering we have been dumped too many times.

2.Dinner is on me我请客
Because it is your birthday today, dinner is on me.

3.Dream on做白日梦
"Perhaps one day I may go on a relaxing holiday."
"Yeah, dream on."

4.Cheat on 作弊，劈腿
I cheated on my exam.
I really hope that my girl friend does not find out that I cheated on her.
I hope the teacher does not find out that I cheated on the exam.
I hope that my friend does not find out her boyfriend cheated on her.

5.Embark on 一般指开始从事某项具有挑战性的任务。
The president embarked on a journey to Asia to visit several countries.

6.I'm on it 我已经跟进了
"If you do your homework, you can go and play."
"I am on it."