1、if 与 unless 的异同
1)通常unless 等于if not 如：
I won’t go unless he comes.= I won’t go if the doesn’t come.
2)在下面的句子中不可做此替换。如：
I’ll be surprised if he doesn’t have an accident. 他要是不出事故，我倒会感到奇怪了。
unless 不能用于“由于未发生B而产生A”的句子，再如：
I’ll be quite glad if she doesn’t come this evening. 要是他今晚不来，我才高兴呢。
2、imagine
1）接名词、代词：You can’t imagine the life on the island.你无法想象岛上的生活。
2）接动名词：She never imagined her going abroad for further education.她从没设想过会出国深造。
3）接从句：You can’t imagine how worried I was those days.你想象不到那几天我是多么焦虑啊。
4）接复合宾语：The boy imagined himself to be a hero. 这男孩把自己想象成了英雄。
[应用] 选择正确答案
I can hardly imagine Peter ______across the Atlantic Ocean in five days.(MET’91)
A.sail B.to sail C.sailing D.to have sailed
Key:C
3、improve
1)用作及物动词，意为“改善，使更好，增进，提高”。如：
improve one’s English/ the living conditions/ one’s method of study/ oneself in maths
提高英语水平/改善居住条件/改进学习方法/提高教学水平
2)用作不及物动词，意为“变得更好，增加”。如：
After two days’ rest his health is improving.
经过两天的休息，他的健康状况在好转。
3)用作名词：improvement of soil土壤改良；make improvement in 在某方面作出改进
[应用]一句多译
①他的中文水平在不断提高。
②这篇文章你最好有所改进。
Key:①His Chinese is improving./ He is improving his Chinese.
②You’d better improve your article./ You’d better make improvement in your article.
点击查看：高中英语知识点大全相关专题