It is the prevention of disease ______its successful treatment that has led to the rapid increase of the world’s population.
Each of the students in No.1 High School, Quanzhou works hard at his or her lessons, ____to go to university some day.
--- You've left the light on. --- Oh , so I have. _____and turn it off.
In my opinion, ______ matters is not one’s looks, but one’s inner thoughts.
______ with danger,the 16-year-old girl was wonderfully calm.
The solution ______ this problem is acceptable. So I am ______ it.