The suffix -ify can be used to change nouns and adjectives into verbs.
solid + ify = solidify
However, sometimes the root word changes before the suffix is added.
peace + ify = pacify
horror + ify = horrify
The suffix -ate can also change nouns and adjectives into verbs, but again the root word often changes as well.
medical + ate = medicate
pollen + ate = pollinate
In this worksheet you can practise adding suffixes to words where the root word also needs to be changed.