1. absolutely!/ definitely!
那当然！
2. it's certain.
那是一定的。
3. it's for sure! / sure thing!
那是一定的！
4. you bet! / you betcha! / you bet your life!
我可以打包票！
5. no doubt! / there's no doubt about it!
毫无疑问！
6. it's in the bag.
已经是囊中之物了。（十拿九稳、跑不掉的。）
7. it's settled. / it's set in stone.
已经定案了。
8. it's a done deal. / it's a dead cert!
已经定案了。
9. sorted!
搞定！（英式俚语）