Hi!
Here I'm posting some exercises about negative prefixes in English. Click on the links to do the exercises.
Remember: negative prefixes are attached to nouns, adjective and verbs to make them negative. Thus, the adjective happy can be made negative by adding the prefix -un, unhappy. The meaning would be similar to the use of not after the verb: She is unhappy = she is not happy.
Main negative prefixes: -un, -dis and -in (-ir, -il, -im)
Examples: agree -> disgree
decent -> indecent
believable -> unbelievable
responsbile -> irresponsible
legal -> illegal
possible -> impossible
http://www.tinyteflteacher.co.uk/learning-english/FCE/word-formation-negatives.html
http://kaj.upol.cz/materialy/lexicology/negprefixes.htm
http://www.nonstopenglish.com/exercise.asp?exid=813
After doing the exercises, let me know how you did down below in the comments box, please.
Good luck!!