Explanation：A written promise or reminder to pay a debt. （借条，借据，欠条）
Example：A: Tina, can I bum 100 bucks out of you? I can write you an IOU.
B: No way, Tom. I have already got too many IOUs from you.
We undercharged Mr. Smith and have to send him an IOU for the extra amount .
I haven' t any money. Can I give you an IOU for $ 10 ?
2. Expression：It takes two to tango。
Explanation：Two parties involved in a certain action or situation. （一个巴掌拍不响）
Example：Your son blames mine for their fight at school but it generally takes two to tango.
We won't be able to get this deal underway unless your company is willing to compromise. It takes two to tango, after all.
Alan: You're always arguing! Stop arguing all the time.
Jane: I can't argue all by myself. It takes two to tango.
Fred: Did you hear? Janice got herself pregnant.
Jill: Well, she didn't do it all by herself. Takes two to tango, you know.
3. Expression：Jack of all trades
Explanation：A person who is skilled in many different areas.（杂而不精的人，样样懂一些的人）
Example：Peter's never stayed at anything long enough to become an expert. He's something of a jack of all trades.
My father could fix cars, build furniture, and program computers—he was a jack of all trades.
Bill can do plumbing, carpentry and a little bit gardening. He is really a Jack of all trades.
Why did you do such a lousy job? You are a Jack of all trades.