1. He has not helped the homeless people for ten years.
=> The last time + S + V ed+ was + time + ago.
= S + have/ has + not + V + since/ for ...
2. I find it is important to learn French
=> It's + adj + (for sb) + to-V
= S + find + it + tobe + adj + to-V
3. This is the most delicious cake he has ever eaten
=> S + have/has + (never) + Vpp + such + a/an + adj + noun
= This is + the + so sánh nhất của tính từ + noun + S + have/has + (ever) + Vpp
4. I started donating books and clothes nine years ago.
=> S + have/ has + Vpp + since/ for ...
= S + started + V-ing + time + ago
5. She became an excellent student from 1975
=> S + have/ has + Vpp + since/ for ...
= S + V2 + O + from time/ time ago