expressions

1. It's common knowledge that...
2. It's a fact (that)..
3. Anyone will tell you..
4. Everybody knows that...
5. It's a well-established fact that
6. Few people would deny that..
7. It's no secret that...
8. I think we can all accept / agree that..
9. It is generally assumed that...
10. It has been scientifically proven that...
    1. In phrases 1, 2, 3, 4, and 5 the speaker is introducing ideas that everybody agrees are true.
    2. The other 5 phrases are a little less strong, saying that a few people might disagree, but nearly everybody does agree with your statement.
    3. Phrases 1, 5, 6 and 10 are good opening phrases for a discursive essay. You can use one of these phrases to establish the importance of the topic before introducing an aspect of the topic that is not agreed.
    4. Phrases 3, 4, 7 and 8 are often used in spoken discussions or debates.
    5. Phrase 10 is saying that somebody has done an experiment that proves your statement to be true. If using this in writing you may want to refer specifically to scientist or the experiment itself in your next sentence.