AIDS is said ______the biggest health challenge to both men and women in that area over the past few years.
.Mary was _________ the letter from Tom,but it didn’t reach her for some reason.
.Hundreds of people leave their village to seek their _________ in cities.
—Johnson failed to get a good job in that company.—He should have _________ the best of chance.
Many new _________ will be opened up in the future for those with a university education.
_________ whenever you like;you are always welcome.