2.省略条件从句或主句, 省略部分的含义仍有所体现. 省略主句时, 表示己不能实现的愿望

　　 　　a. You could have done it yourself (if you had wanted to).

　　 　　b. I wouldn’t smoke (if I were you).

　　 　　c. If my old friends were with me! (要是老朋友和我在一起该多好啊)

　　 　　d. If you could have seen the wonderful film!

1.条件从句省略if: 在书面语中, 如果条件从句中的谓语中有were, had, should等词, 可将if省略, 而把were, had, should放在句首

　　 　　a. Were I you (=If I were you ), I would get up early very early.

　　 　　b. Had you arrived (=If you had arrived ) at the station ten minutes earlier yesterday, you could have caught the train.

3.表示与将来事实相反的情况时, if从句的谓语形式是: ①.完全动词过去式 (be的过去式通常用were);　 ②.should +动词原形;　 ③.were to do. 其中②, ③种情况都含有“出乎意料之外”之意; 主句的谓语的形式是: should / would / could / might +动词原形

　　 　　a. If she should invite me tomorrow, I should go to the party.

　　 　　b. If it rained / should rain / were to rain tomorrow, our picnic would be put off.

　　 　　c. If I saw him tomorrow, I would pass your note to him.

　　 　　d. I might come back if I were to miss the train.

2.表示与过去事实相反的情况时, if从句的谓语用had done形式, 主句的谓语用should / would / could / might + have done的形式

　　 　　a. If she had invited me yesterday, I should have gone to the party.

　　 　　b. I would have checked my paper again if I had had more time at yesterday’s exam.

　　 　　c. If you had taken the teacher’s advice, you would not have failed in the exam.

1.表示与现在事实相反的情况时, if从句的谓语用动词的过去式 (be动词的过去式多用were, 而不用was), 主句的谓语用should / would / could / might +动词原形 (should多用于第一人称, would多用于二三人称, could / might可用于所有人称)

　　 　　a. If I had more time, I should study computer better.

　　 　　b. If he were not so busy, she would attend the meeting this afternoon.

　　 　　c. If they didn’t take exercises every day, they wouldn’t be so healthy.

　　 　　d. If you went to bed earlier, you would not be so sleepy in the morning.

　　 　　e. If she invited me, I should go to the party.

2.表示命令

　　 　　a. Everybody leave the room.

1.表示祝愿

　　 　　a. Long live our country.

　　 　　b. May you succeed.

　　 　　c. May you be happy all your life.

虚拟语气的用法

2.作为实义动词时, 可用于: dare to do sth

　　　　 a. Little Jane didn’t dare to go alone.

　　　　 b. Did you dare to go out alone at night ?

第十章：虚拟语气

概　 述

1.作为情态动词时, 主要用于否定句和疑问句中, 不用于肯定句中

　　　　 a. Little Jane dared not go alone. =Little Jane didn’t dare to go alone.

　　　　 b. Dare you go out alone at night ? =Did you dare to go out alone at night ?