It depends on what you are communicating. You could add -ed, -ing, -er, for example.
after
The prefix of the word "postdoctorate" is "post-" and the suffix is "-ate."
Postdoctorate has a prefix of 'post' meaning after, and a suffix of 'ate' making it an adjective/descriptive word.
Paid is the root word. Post- is the suffix.
after birth. Post means after. Natal means birth.
What do you mean? Do you know what a "sufix" (it's actually spelled "suffix") is? The word makes no sense in this context. Perhaps you mean "acronym", in which case the answer is "PTSD".
Ah, let's take a moment to appreciate the word "posture." The prefix is "post-" which means after or behind, the root is "post" which refers to position or place, and the suffix is "-ure" which is used to form nouns. Just like painting a happy little tree, breaking down words can be a peaceful and enlightening experience.
"Mission" is a root word. It has neither a suffix nor a prefix. Transmission and missionary are words with a prefix or suffix attached to the root word "mission."
The suffix for undo is to not do.
the suffix is on
There is no suffix in misjudge.
The suffix is -er, meaning "one who campaigns."