7. The last time my mother wrote to me was 2 weeks ago.

8.This is the first time they have met the President.

9.His son started working on the farm 12 hours ago.

10.I have never eaten Sashimi before

$\text{7.}$The last time my mother wrote to me was 2 weeks ago .

→ S + hasn't/haven't + Vpp 

→ The last time + S + Ved/cột 2 + was + time 

$\text{8.}$This is the first time they have met the President .

→ S + has/have + never + Vpp + ..... + before

→ This is the first time + S + has/have + Vpp 

$\text{9.}$His son started working on the farm 12 hours ago .

→ S + started/began + V-ing/to V + when/in/on/ago/... + time 

→ S + has/have + Vpp + for/since + time 

$\text{10.}$I have never eaten Sashimi before . 

→ S + has/have + never + Vpp + ..... + before

→ This is the first time + S + has/have + Vpp