fact
1.in fact, as a matter of fact和in point of fact三种表达方式都作“实际上、其实”解。as a fact也有人用，但不算正当，该避免。as a matter of fact含有“虽然好像不是这样而实际是这样”的意思。
2.在谈话里有时用matter of fact代替as a matter of fact。例如：Matter of fact, I wouldn't do it if I were you.
3.下面第一句最正常，其他三句都有些口语性质：
- The fact is that they do not know him.
- The fact is, they do not know him.
- Fact is that they do not know him.
- Fact is, they do not know him.
4.fact有时指“实有的东西”。例如：The dominating fact of his early life was his mother.
5.the facts of life有时是“人生的一切事”，有时是“性和生殖基本知识（指受胎、分娩等）”。
