Adverbs of frequency are words like: always, often, sometimes, rarely, never. They answer the question 'how often...?'
How often do you go to the gym?
I always go to the gym.
I often go to the gym.
I sometimes go to the gym.
I rarely go to the gym.
I never go to the gym.
Where do they go in a sentence?
Adverbs of frequency generally occupy three positions in a sentence - all in relation to the verb.
1. Before the main verb
In the majority of cases, the adverb of frequency goes before the main verb.
Helen always starts work at seven.
She usually went to school by bus.
2. After the verb when the main verb is 'be'
If the main verb is a form of 'be' (am, are, is, was, were), the adverb of frequency comes after.
Helen isn't always happy with this.
They are never late for anything!
3. Between the auxiliary verb and the main verb
If the sentence has two verbs - an auxiliary verb and a main verb - the adverb of frequency goes between them.
Helen has always hated early starts.
She doesn't often go to school by bus.