How long ___ English ?

"How long" is an interrogative phrase used to inquire about the duration or length of time. It introduces the question and indicates the desired information.

"have you been learning" is the present perfect continuous tense. It is used to describe an action that started in the past, is still ongoing in the present, and may continue into the future. The structure "have + subject + been + verb (-ing form)" is employed in the present perfect continuous tense.

"English" is the direct object of the sentence, indicating the specific language being referred to.

Putting it all together, the complete sentence "How long have you been learning English?" is a grammatically correct interrogative sentence that inquires about the duration of someone's ongoing process of learning the English language.