Question

Preciso de 15 frases afirmativas no present perfect tense

Answer 1

No Present Perfect Tense, usamos:
Afirmativo:
o verbo HAVE + o verbo no passado particípio. Ex:
You HAVE GONE.

Interrogativo:
o verbo HAVE vem para frente do pronome. Ex:
HAVE YOU gone?

Negativo:
acresenta-se um NOT depois do HAVE. Ex:
You HAVE NOT GONE ou You HAVEN'T GONE.

No caso das suas questões, ficaria:

We have helped the animal rescuse project.
Interrogativo: Have we helped the animal rescuse project?
Negativo: We have not helped the animal rescuse project.

She has just arrived home from Costa Rica.
Interrogativo:Has she just arrived home from Costa Rica?
Negativo: She has not just arrived home from Costa Rica.

I have gone to the websites you listed and contacted Unicef.
Interrogativo: Have I gone to the websites you listed and contacted Unicef?
Negativo: I have not gone to the websites you listed and contacted Unicef.

My brother has changed his volunteer work.
Interrogativo: Has My brother changed his volunteer work?
Negativo: My brother has not changed his volunteer work.
Obs: depois dessas dicas voce podera fazer as frases.

Answer 2

He has broken his leg.
We have bought new clothes.
She has written a letter to her friend who lives in Madrid. 
He has had a terrible headache
They have finished the homework
That rabbit has appeared on our garden.
He's studied law
She's been here.
We've worked a lot. 
She's given birth to a boy.
I've broken a glass
Have you already talked to your boss?
Has he found his wallet?