Помогите составить 5 полож. и 5 отриц. предложений в present perfect

1. i have just opened the window

i haven't opened the window yet

2. peter has just come back home

peter hasn't come back home yet

3. mary has played the piano since 10

mary hasn't played the piano since 10

4. they have been to London

they hve never been to London

5. we have already done our homework

we haven't done out homework yet