Working abroad for many years, he has made a big _______ and started a company of his own.

This is not an economical way to get more water; ____, it is very expensive.

You can’t park here, sir. It is ____ for the ambulances only. 

When I was about to go out, something unusual _______ my attention.

The more one is ______ the English－speaking environment，the better he or she will learn the language.