填空题

People generally call each other by their (1) much sooner in their acquaintance than people do in other walks of life. Taking that liberty too soon has (2) many doors for the offender. Therefore, one must sense the proper moment to drop formal address and adopt subtle measures to (3) unwelcome intimate address. If you have been accepted wholeheartedly into a group, however important first names are in the world’s eyes, it would be conspicuous for you to continue (4) a certain time to call them by their last names, (5) Mr. Robinson and Mrs. Harvin.

3（）