Find the mistake(s)

I have thirty sheep in the meadow.
Where are the grey stones?
Do you need this chair?
Can you show me?
I feel happy today.
How many languages do you speak?
We cook food for the family.
Are these shoes yours?
The farmer has eight horses.
The mountains seem bigger when it is dark.
He protects me against danger.
My back hurts.
It feels weird to be back.
The cows walk on green fields.
My life lasts long.
The fire burns really long.
Tomorrow it will rain.
I am touching you with my finger.
My son is seven years old.
Shut the door.
I don’t understand it well.
Why did you do that?
I love to write.
The sun shines today.
She needs money for school.
My dog is happy for me.
Can your hear me?
Here you need to turn right.
Do you have time for me?
The children play with toys.
I think it’s really important for you.
We walk through the woods.