must, mustn't or needn't?

Gap-fill exercise

Choose the correct verb from the list. Then press "Check".

Lulu is over there. You look for her.
You eat too many chocolates.
This cake isn't for us. We eat it.
Your test is great. You do the correction.
We can go by car, so we wait for the bus.
We haven't got candles. We buy candles for the birthday cake.
They're poor. So their children buy silly things.
They've got a big garden with lots of flowers. They buy flowers.
You laugh about a mistake.
This book is great. You read it.
I can do it. You help me.
We speak German in the English lesson.