They’re ______ choosing a cautious policy in order to avoid a risk in such an important event.
It was at midnight ______ he got to his friend’s house.
The global warming is more and more serious, for which human beings ______.
--- Grace won’t like it, you know. ---______ ? I don’t care what Grace thinks.
It is said in the book that Tomas Edison (1847-1931) _______ the world leading inventor for thirty years.
The old couple preferred a flat in a small town to ______ in so large a city as Chongqing.