You were working too hard. You’d better keep a ________between work and relaxation.

Glad to meet you and here is my card. Let’s keep in______ later.

—Believe it or not, last month in America I came across the girl whose photo was in the drift bottle got three years ago .   —Really？That’s the most surprising          I’ve ever heard of！

The _____ stuck on the outside of the envelope said "By Air".

As a candidate（候选人）, you must try to make a good         on everyone if you want to win the election.