Adverbs of frequency describe how often something happens . There are two types of adverbs of frequency: D efinite : We exactly know how often something happens, and use them at the end of a sentence. I ndefinite : We do not know how often something happens, and use them before the main verb, after the modal verb or first auxiliary verb, or after the verb to be. Here is the list of some adverbs of definite frequency with examples: