1.must 表示推測時(shí),其后的反意疑問句要根據(jù)must后的謂語動(dòng)詞一致.
你查到的幾個(gè)句子有兩個(gè)對,中間那個(gè)不對.
You must have studied English for three years, haven't you? / didn't you?
這個(gè)句子只能用haven't , 不可以用didn't.
2.在前面的陳述句中有具體的過去的時(shí)間狀語時(shí)才用didn't .所以第三個(gè)句子是正確的.
He must have finished it yesterday, didn't he?
那么你的單選題：He must have learn English for three years,___?
A.hasn't heB.haven't heC.mustn't heD.didn't he
正確答案就是A.
如果有疑問就hi我.祝你學(xué)習(xí)愉快!