Look, the old man who is playing _______ guitar is ______ university teacher.

Little children should go to school to learn something.______, they should learn how to behave well in social life.[ ]

Great changes have taken place in Cangnan. We’re sure Cangnan will be even_____ tomorrow.

We had fun ________ the robots do many different kinds of things.

My son has changed so much that I could hardly __________ his voice on the phone.