Question

Please tell, how to distinguish and use negative prefixes in, im, il, ir, un, dis, et. for different cases?
Thanks in advance...

Answer 1

For "un", it is to reverse a process.  You can tie, then untie.  You can do, then undo.  Hook, then unhook.

"in" "im" "il" "ir" "dis" are usally opposites with no connection with what happened in the past.

In: Conceivable (able to be understand) and inconcievable (beyond understanding).  Capable (can do) and Incapable (can't do)

Im: Perfect and Imperfect (not perfect).  Possible and Impossible (not possible)

Il: Logical and Illogical (not logical).  Literate (able to read) and Illiterate (unable to read)

Ir: Reverent (gives respect) and Irreverent (doesn't give respect).  Responsible and Irresponsible (not responsible)

I don't recognize "et" though, can't think of any words for this prefix unless you mean etcetera which is usually abbreviated etc.

Hope this helps :)