Adverbs of indefinite frequency tell us how often something happens.

Common examples are: always, ever, usually, normally, often, frequently, seldom, never etc.

• I am never late for office.
  
• Have you ever been to the US?
  
• I often work late.
  

Position

Adverbs of indefinite frequency go in mid position. They are normally placed after the auxiliary verbs and before other verbs. When there are two auxiliary verbs, the adverb goes after the first.

• I always get up early. (adverb + main verb)
  
• I am seldom late for work. (is/am/are/was/were + adverb)
  
• We frequently visit them. (adverb + main verb)
  
• I often read comics. (adverb + main verb)
  
• I have never seen a dolphin. (auxiliary verb + adverb + main verb)
  

Points to be noted

1. Usually, normally, often, frequently, sometimes and occasionally can also go at the beginning or end of a clause.

• We visit them occasionally.
  
• Often we trust the wrong person.
  

2. Always, ever, rarely, seldom and never can go only in mid position.

• They never admitted their fault.
  
• You can always trust him.
  

However, always and never can begin imperative clauses.

• Always look before you leap.
  
• Never ask her about her age.