Peter ________ at this job since he graduated from college.
In the global economy, a new drug for cancer, ______ it is discovered, will create many economic possibilities around the world.
Anyone, once ____ positive for H7N9 flu virus, will receive free medical treatment from our government.
(2013·北京卷)I took my driving license with me on holiday, I wanted to hire a car.
“You can’t judge a book by its cover,” ________ .
(2013·安徽卷)From space, the earth looks blue. This is about seventy-one percent of its surface is covered by water.