`1`. Have been.
Có severl times `->` Chia thì HTHT.
`2`. Have studied.
Có so far `->` Dấu hiệu thì HTHT.
`3`. Have seen.
Có recently `->` Dấu hiệu thì HTHT.
`4`. Have you seen.
`5`. Have done.
Có already `->` Dấu hiệu thì HTHT.
`6`. Have never gone
Có never `->` Dấu hiệu thì HTHT.
`7`. Haven't seen.
`8`. Have ever meet.
`9`. Were.
Có in the past 3 day `->` Chia thì QKĐ.
`10`. Have visited.
`11`. Found
Có in the past 50 years.
`12`. Has improved/ left.
Cấu trúc : HTHT + since + QKĐ.
`13`. Bought/ Have worn.
Vế 1 có last (Dấu hiệu thì QKĐ), vế 2 có yet. (Dấu hiệu thì HTHT)
`14`. Haven't seen/ left.
Cấu trúc như câu `12`
`15`. Have just moved.
`#Study well`
