It is useful to be able to predict the extent _____ a price change willaffect supply and demand.

Mr. Smith has been working in China _______2000.[ ]

We all like ____ math teacher because she is very kind.

3- junior high school life will be over . I will remember those things and teachers ____ are unforgotten .

You looked so tired this morning. How much_____ for the work? —Oh, I was just helping my friend.