The suffixes -en and -ify can be used to change adjectives (describing words) into verbs (action or doing words).
tight + en = tighten
note + ify = notify (the 'e' is dropped before the suffix is added)
The suffix -ise can also be used to change adjectives into verbs.
special + ise = specialise
public + ise = publicise (the 'c' sounds like an 's' in the new word)
The suffix -ise can also change nouns (naming words) into verbs.
advert + ise = advertise
Nouns ending in 'y' drop the 'y' before the suffix is added.
memory + ise = memorise
harmony + ise = harmonise
Some people spell the -ise suffix -ize instead. This is normal in America but in Britain the -ise spelling is usually preferred.
In this worksheet you can practise choosing the correct suffix to change nouns and adjectives into verbs. You may need a dictionary to help you.