Frequency adverbs

        The adverbs are the words that describe an aspect of the verb. They are usually placed at the end of the sentence.

        Frequency adverbs are the ones that express how many times an action is repeated. Depending on the frequency a different adverb will be used.

•  0% - Never 

• 20% - Seldom, Hardly ever, Rarely

• 50% - Sometimes 

• 80% - Usually, Often, Generally, Normally

• 100% - Always

They are always placed before the main verb, except with the verb “to be” in which case they will be placed after it.

        — They never stay home alone.

        — They are never home alone.

They are an indicator of present simple, they are almost always used with sentences in present simple.