what is the complete verb phrase? and helping verb?
Who has been doing research on early polar flights?
Is it has research?
I can not include any of the words that may separate the parts of the verb phrase
The complete verb phrase is has been doing.
Research in this sentence is a noun and the direct object of "doing."
The complete verb phrase in the sentence "Who has been doing research on early polar flights?" is "has been doing research."
The helping verb in this verb phrase is "has been." To identify the helping verb, it is important to look for the word that is used to form the verb tense. In this case, "has been" is used to form the present perfect continuous tense, indicating that the action of doing research started in the past, continues in the present, and may extend into the future.