1. We can say a lot of things about those _______________ （毕生致力于诗歌的人）: they are passionate, impulsive, and unique.
　　2. Mary couldn't have received my letter, _______________ （否则她上周就该回信了）.
　　3. Nancy is supposed to _______________ （做完化学实验）at least two weeks ago.
　　4. Never once _____________ （老两口互相争吵）since they were married 40 years ago.
　　5. ____________________ （一个国家未来的繁荣在很大程度上有赖于）the quality of education of its people.

　　答案与解析：
　　1.who have devoted/dedicated their lives/themselves to poetry
　　2.or/otherwise she should/would have written back last week.
　　3.have finished the chemical experiment(s)
　　4.have the old couple quarreled with each other
　　5.The future prosperity of a nation depends/rests largely/mainly on/upon