The headmaster has got a good education ___ so the school is doing well.

Some countries are increasing their use of natural gas, and other forms of __________. 

一Tell us, Mark ,what is the ____ of the American Civil War?一 Well, is it because the black slaves wanted freedom?

If you want to get more information on how to apply for studying overseas, you can go to the office of foreign      for details.

The rocks are very big with _____ of colors on them.