1. Prefixes

2. A prefix is placed at the beginning of a word to modify or change its meaning.
With Adjectives:
They usually give adjectives a negative or an opposite meaning.
For example:
This chair is comfortable. ( adj)
This chair is uncomfortable. ( adj)

3. If a root starts with:
1) m or p:
in + mature =immature
in +patient = impatient
2) r:
in + replaceable = irreplaceable.
3) L:
in+ legal =illegal

4. 2) With verbs: -The prefixes un- and dis- can form the opposites of verbs. e.g. untie - disappear -The prefix re- can mean again or back. e.g. retype- rewind