1.opportunity: a favorable moment or occasion (for doing something)
　Examples:
　　It will give you an opportunity to meet all kinds of people.
　　Don't let slip any opportunity to practice your English.

2. claim: say that (sth.) is true or is a fact without having any proof
　Examples:
　　Jean claims to own a car but I don't believe her.
　　He claimed that he had done the work without help.

3. let alone: not to mention
　Examples:
　　I have not even read the first chapter, let alone finished the book.
　　The baby can't even walk, let alone run.

4. discourage: prevent (an action)
　Examples:
　　We discourage smoking in this school.
　　We tried to discourage him from climbing the mountain without a guide.

5. foster: help (something) to grow or develop
　Examples:
　　Cooperative learning fosters a spirit of cooperation.
　　The mother tried to foster her son's interest in music by taking him to concerts when he was young.

6. try out: test to find out about quality, worth, effect, etc.
　Examples:
　　I want to try out several of the new singers for the part.
　　The new engine must be thoroughly tried out before being out on the market.

7. focus on: direct one's attention to
　Examples:
　　Today we're going to focus on the question of homeless people in London.
　　As we can't study all the resources, I propose we focus attention on one of them.

8. academic: scholarly, theoretical, not practical
　Examples:
　　Academic exchanges are an important part of cultural exchanges between two countries.
　　His theory received little attention because he was unknown in the academic world.

9. grateful: feeling or showing thanks
　Examples:
　　I was most grateful to John for bringing the books.
　　We are grateful to our neighbors for help in time of trouble.

10. sign up: sign an agreement to take part in something
　Examples:
　　We will not have the picnic unless more people sign up.
　　How many people signed up for this course.

11. lose oneself in: be extremely interested in something
　Example:
　　On a dull winter afternoon, Harry would sit by the fire and lose himself in a book.
　　Boys tend to lose themselves in computer games.

12. fall into: pass into a specified state
　Example:
　　You have fallen into a bad habit of repeating yourself.
　　If you fall into heavy smoking, you'll get healthy problems.

13. capable: having ability of doing or the power to do
　Examples:
　　She is extremely capable and dependable.
　　This computer is capable of storing millions of bits of information.

14. appropriate: correct or suitable
　Examples:
　　Plain, simple clothes are appropriate for school wear.
　　It seemed appropriate to end with a joke.

15. lead to: have as a result; cause
　Examples:
　　A bad cold can lead to pneumonia.
　　Hard work leads to success.