Doing your homework is a sure way to improve yor test scores, and this is especially true ____ it comes to classroom tests.
Jack wasn't saying anything, but the teacher smiled at him ________ he had done something very clever.(2011·湖南)
One third of the country ________ covered with trees and the majority of the citizens________black people.( 2011·湖南)
She showed the visitors around the museum, the construction ________had taken more than three years.(2011·江西)
If better use is ________ of your spare time, you'll make good progress in doing your business.
The couple ________ a health centre in Cambodia,________ their seven year old son was born.