More and more people in Shanghai choose to go to work__________ underground.
The Greens used to live in London, but they ___________ in Beijing so far.
My father ___________________________ when he was in his twenties.
It is dangerous ____ you ______ a close look at the tiger in the zoo.
Take the paper with you. The details we ought to pay attention to ________ on it already.
This problem worried her so much that she didn’t know ___________ with it..