About ______ of the surface of the earth is covered with water.

What do you think of the twin sisters—They are quite different. One is outgoing, __________ is very serious.

The teacher came in ,________．

Readers are required to _________ the rules of thelibrary and mind their manners

Mum, there is _______ milk in the glass.—-Let’s go to the supermarket to buy some.