a welcome visitor的用法和样例：
- She was a welcome visitor.
- We've never seen people who are so excited, first of all to be in the presence of a foreigner, and not be prejudiced in anyway against us, but to look at us as a welcome visitor to this country.
- A welcome respite from hard work.
- Our ambition is to give them a beau ideal of a welcome.
- He nodded me a welcome/nodded a welcome to me.
- He shook hands with me vigorously and smiled a welcome.