1.
You use ~ to say that something is obviously true, for example because you have seen evidence of it yourself.
The man wore a bathrobe and had ~ just come from the bathroom...
The two Russians ~ knew each other.
= clearly, obviously
ADV: ADV with cl/group, ADV before v
2.
You use ~ to show that you think something is true or have been told something is true, but that you are not sure, because you do not have enough information or proof.
From childhood, he was ~ at once rebellious and precocious...
= apparently
ADV: ADV with cl/group, ADV before v
3.
You can use ~ to introduce a statement or opinion and to emphasize that you feel that it is true or correct. (FORMAL)
Quite ~, it has nothing to do with social background.
ADV: ADV with cl emphasis