介绍:

deal n.
交易；买卖；
She got a new car for $1000! That was really a good deal!
她一千美金买了辆车！真是捡了个大便宜！

a big deal
①重要的事情
He got promoted last month. That was a big deal to him!
他上个月升职了。这对他来说是个大事。

②重要的人物
I was kind of a big deal in high school.
高中时候我可是风云人物。

③有什么大不了的！（表示不屑）
A: Hey. I could do one-arm push-ups.
喂，我能做单手俯卧撑.
B: Big deal! I can do push-ups without using my hands!
有什么大不了！我可以不用手做！

deal in
经营；做… 的生意
My dad deals in medical supplies these days, selling X-ray and MRI machines to hospitals.
我爸爸做医疗用品的生意，就是往医院卖X光和核磁共振的一些设备。