Betty enjoys playing________ piano, but her brother is interested in playing _______ football.

Many gases inthe atmosphere actually heatenergy that escapes from the Earth’s surface back to the earth

What did your teacher say this morning—-She told us _______make faces in class.

What are you worrying about? —It is ________ there is any chance of being infected by AH1N1 virus

wo countries agreed to ________ their differences and work together for peace, which has a positive effect on the international situation