I’m sorry I can’t go for the picnic with you this Sunday. I have to go to see my grandpa.— ______

_________ a day do you brush your teeth —Twice.

下列各句中，没有语病的一句是

David is taller than ________ in his class.

These are all good team sports and will help you ______ your strength and you will meet lots of people atthe same time.