—Mary was being badly treated when John happened to pass by and helped her out.—I think it was not a pure ________but had been well planned.

There are certain _______when you have to interrupt people who are in the middle of doing something.

 It’s said that a(n) _________of $1,000 will be offered to anyone who helps to find the escaped prisoner.

Being able to speak another language fluently could be a great ___when you are looking for a job. 

Ancient Greeks were responsible for many of the _______ in science and other fields.