_____ medicine works in a human body is a question ____ not everyone can understand fully.

I hear we will have an vacation.

Our English teacher is our favoriteShe’s kind and humorous, but ________, she is strict with us.[ ]

The news spread yesterday ______President HuJingtao had inspected HongKong army during the 15th anniversary of HongKong returning to China.

The book ____bythe young writer sells well. It is popular among middle school students.