1. We (be) were students, we (learn) have learned english for 4 years
HTHT : S+have/has+`V_3`
Dấu hiệu : "For + khoảng thời gian-4years"
2 : Has he already(do) done his home work? no, he hasn't.he(write) has written it lately
HTHT : S+have/has+`V_3`
Dấu hiệu : "already" , "lately" , ở câu trả lời có thêm "hasn't"