`1`.Tom hasn't forgot to do his homework for three months

`\rightarrow` Thì HTHT ( PĐ ) : S + haven't / hasn't + VpII

`\rightarrow` For + Khoảng thời gian : Bao lâu

`\rightarrow` Forget + to do sth : Quên làm gì

`2`.They have made origami as a hobby since last February

`\rightarrow` Thì HTHT : S + have / has + VpII

`\rightarrow` Since + Mốc thời gian : Từ khi nào

`\text{@ Tails347}`

Đáp án :

1.the last time tom forgot to do his homework was three months ago

→Tom hasn't forgotten to do his homework for three months

2.they started making origami as a hobby last february

→They have made origami as a hobby since last February

Giải thích : 

1.the last time + S + V2/ed + O→S + have/has(not) + Vp2 + O

2.Started/began + V-ing/to V→have/has + Vp2