--- Why are you taking a bag with you?--- I’m going to buy something. The supermarkets don’t _____ free plastic bags to shoppers to protect the environment.
He _______ go out with his parents, but now he _______ staying at home alone.
----How do you like the two pairs of shorts?----They don’t fit me well. They are _______ too long _______ too short.
________ my surprise, the twins have nothing _______ common.
---Do you know sound travels very fast?----Yes. But light travels _______ sound.
Paper-making is one of _______ of ancient China.