---What did Lu Xun do after he gave up medicine?---He devoted ______writing all his life.
We are often told _____ at people in trouble.
The old woman kept one black dog and two white ____.
–Is this orange radio _____? -- No, it belongs to ______.
______ book on the desk is _____ useful one.
–How many _____ are there in your school, Tom? -- Two.