К каждому из этих предложений составить отрицание. Не через переводчик.
I start doing my homework.
I started doing my homework.
I will start doing my homework.

She looks around.
She looked around.
She will look around.

They agree to go for a walk with us.
They agreed to go for a walk with us.
They will agree to go for a walk with us.

I don't start doing my homework.I didn't start doing my homework.I won't start doing my homework.She doesn't look around.She didn't look around.She won't look around.The don't agree to go for a walk with us.The didn't agree to go for a walk with us.They won't agree to go for a walk with us.