She sat at the desk and set about _____ aletter to her friend.

Poor thing! Jack________ down while he________ on the ice. He got hurt badly.

This kind of material can be used to ________ plastics.[ ]

You know that you were driving at 100 kilometres an hour, _____?— No, officer, I couldn’t have been. This car can’t do more than 80. [ ]

Tom isn’t _________ Jack．