英语虚拟语气1.Electriccurrent flows through a conductor as though

英语虚拟语气
1.Electriccurrent flows through a conductor as though it _____(be) a fluid.答案为were,

as thoygh it were a fluid 好像是液体【其实不是】,表示一个虚拟,在正规英语虚拟语气中,be动词一律用were.
再问： 那它是和现在事实相反咯？？
再答： 客观事实当然与现在相反。
再问： 既然是客观事实，不就应该用一般现在？？
再答： 虚拟语气【时态全部往后退一步】
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.

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.