Whenever I think of my childhood, I'll always feel that the period of free time seem to have passed ________
It is quite common for a working man to make ______ for his old age by putting aside enough money to live on.
Classification is a useful ______ to the organization of knowledge in any field.
He was ______ determined than you, but he turned out to be the first to back out.
This article was written ______ for China Daily.
You should have put the milk into the icebox, I expect it ______ undrinkable.