用 I have been doing 或I have done 填空。 You have a friend who is learning Japanese. You ask: How long ________(you /learn) Japanese?
用 I have been doing 或I have done 填空。 You have just arrived to meet a friend. She is waiting for you. You ask: __________ (you/wait) for a long time?
用 I have been doing 或I have done 填空。 A friend of yours is a teacher. You ask: How long _________________ (you/teach)?
用 I have been doing 或I have done 填空。 Tom looks very tired. You ask:______________(you/work) hard?