Exact means correct in every detail. For example, an exact copy is the same in every detail as the thing it is copied from.
approximate , inexact , vague , imprecise
I don't remember the exact words.
我不记得确切的话了。
The exact number of protest calls has not been revealed.
抗议电话的确切次数尚未披露。
an exact copy of the text.
一份精确的文本复印件。
Predicting earth tremors is not an exact science.
预测地动不是一门精确的科学。
You use exact before a noun to emphasize that you are referring to that particular thing and no other, especially something that has a particular significance.
I hadn't really thought about it until this exact moment.
直到此时此刻我才真正开始考虑它。
to be exact
You say to be exact to indicate that you are slightly correcting or giving more detailed information about what you have been saying.
A small number – five, to be exact – have been bad.
一个小数目–确切地说是5–已经很糟了。
exacts , exacting , exacted
When someone exacts something, they demand and obtain it from another person, especially because they are in a superior or more powerful position.
Already he has exacted a written apology from the chairman of the commission.
他已经通过强行要求得到了委员会主席的书面道歉。
If someone exacts revenge on a person, they have their revenge on them.
She uses the media to help her exact a terrible revenge.
她利用媒体帮助她实施一次可怕的报复。
If something exacts a high price, it has a bad effect on a person or situation.
The sheer physical effort had exacted a heavy price.
纯粹的体力支出已付出了沉重的代价。