Helping verbs or auxiliary verbs such as will, shall, may, might, can, could, must, ought to, should, would, used to, need are used in conjunction with main verbs to express shades of time and mood. The combination of helping verbs with main verbs creates what are called verb phrases or verb strings. In the following sentence, "will have been" are helping or auxiliary verbs and "studying" is the main verb; the whole verb string is underlined:

• As of next August, I will have been studying chemistry for ten years.

Students should remember that adverbs and contracted forms are not, technically, part of the verb. In the sentence, "He has already started." the adverb already modifies the verb, but it is not really part of the verb. The same is true of the 'nt in "He hasn't started yet" (the adverb not, represented by the contracted n't, is not part of the verb, has started).

Shall, will and forms of have, do and be combine with main verbs to indicate time and voice. As auxiliaries, the verbs be, have and do can change form to indicate changes in subject and time.

• I shall go now.
  
  
• He had won the election.
  
  
• They did write that novel together.
  
  
• I am going now.
  
  
• He was winning the election.
  
  
• They have been writing that novel for a long time.