He moved to a big city to try his __________.
The book is very valuable to us. That is to say, The book is of________.
-----I am tired of learning English all day long. ------So am I. ____________.
____you have got a chance, you should make full use of it.
______, people are beginning to realize how serious this situation is.
When I got home last night, I was frightened to find that in front of my door____.