If one has never tasted bitter, he or she does not understand _____ is sweet.[ ]

This music ________ great.

The inspector ____ his fingers over the sheet of newspaper. There were some marks on the surface of the paper. [ ]

What do you think of summer in Nanjing—Well, it’s sometimes ______ hot and sometimes thereis ______ rain.

What are you searching the Internet for — I am trying to find out _______.