Fill in the blanks with an appropriate verb form:

How long ……………………… a painter ?

have you been

The correct verb form to fill in the blank is have you been. The present perfect tense of the verb "be" is have been. The context of the sentence indicates that the speaker is asking about something that has been happening for a period of time, so the present perfect tense is the most appropriate tense to use.

The other options are incorrect.

• Are you is the present tense of the verb "be".
• Were you is the simple past tense of the verb "be".
• Was you is not a grammatically correct form of the verb "be".