` 17 `. He hasn't eaten seafood for ` 3 ` months.

` 18 `. They last played tennis ` 2 ` weeks ago.

` 19 `. She has not met him since last Sunday.

` 20 `. We last spoke to him in ` 2012 `.

` 21 `. I haven't gone to Da Lat since ` 2010 `. 

` - ` Cấu trúc thì hiện tại hoàn thành: S + has/have (not) + V3 + O.

` - ` Cấu trúc Last: S + last + V2 + O + ....

- Chúc cậu học tốt.

$\text{17. He hasn't eaten seafood for 3 months.}$
$\text{18. They last played tennis 2 weeks ago.}$
$\text{19. She has not met him since last Sunday.}$
$\text{20. We last spoke to him in 2012.}$
$\text{21. I haven't gone to Da Lat since 2010. }$
$\text{Công thức :}$
$\text{Thì QKĐ + cấu trúc last : }$
$\text{S + last + V}$$^{2}$ $\text{+ O + ... }$
$\text{Thì HTHT :}$
$\text{S + has / have (hasn't / haven't) + V}$$^{2}$ $\text{+ O + ...}$