when a stick is partly in a glass of water,it lo

when a stick is partly in a glass of water,it lo
k as thought it were broken中,为什么从句中用 were broken

这属于虚拟语气,因为后边这句说的不是真的现象.具体原因如下；
虚拟语气
一、考点聚焦
1、虚拟语气用于条件状语从句中
（1）表示与现在事实相反的假设,条件状语从句中的谓语动词用“过去式（be动词的过去式用were）”,而主句中的谓语动词用“would / should/ could / might + 动词原形”.如：
\x09If I were a boy, I would join the army.
\x09If the had time, she should go with you.
\x09（2）表示与过去的事实相反,条件状语从句中的谓语动词用过去完成时,主句中的谓语动词则用“would / should / might / could + have +过去分词”.如：
\x09If he had taken my advice, he would have succeeded in the competition.
\x09（3）表示与将来事实相反,条件状语从句中的谓语动词一般过去时或should(were to) + 动词原形,而主句中的谓语动词则用would / should/
\x09could might + 动词原形.如；
\x09If it were to rain tomorrow, the football match would be put off.
\x09（4）当条件状语从句表示的行为和主句表示的行为所发生的时间不一致时,动词的形式要根据它所表示的时间作相应调整.如：
\x09If they had worked hard, they would be very tired.(从句说的是过去,主句指的是现在)
\x09以下表格是虚拟语气用于条件状语从句中时,主句和从句谓语动词的形式：
\x09条件状语从句\x09主 句
与过去事实相反\x09had + 过去分词\x09should /would/could/might + have + 过去分词
与现在事实相反\x09一般过去时(be用were)\x09would/should/could/might + 动词原形
与将来事实相反\x09一般过去时或should(were to) + 动词原形\x09Would/should/cold/might + 动词原形
\x09有时侯在使用时可省略if,句子则可换成下列形式,即“were / had / should +主语”.如：
\x09Were I a boy, I would join the army.
\x09Had he taken my advice, he would have succeeded.
\x09Were it not for the expense, I would go to Britain.
\x092、虚拟语气用于名词性从句
\x09（1）虚拟语气在宾语从句中的运用.
\x09①“wish + 宾语从句”表示不能实现的愿望,译为“要是……就好了”等.表示现在不能实现的愿望,从句中的谓语动词用一般过去时；表示将来不能实现的愿望,从句中的谓语动词用“would/could + 动词原形”；表示过去不能实现的愿望,从句中的谓语动词用“had + 过去分词”或“could(should) + have + 过去分词”.如：
\x09I wish it were spring all the year round.
\x09I wish I had known the answer.
\x09I wish I could fly like a bird.
\x09②在表示建议、要求、命令等的动词suggest、advise、propose、demand、require、insist request、command、order等后的宾语从句中,谓语动词用should + 动词原形或是动词原形.如：
\x09She suggested we (should)leave here at once.
\x09The doctor ordered she should be operated.
\x09（2）虚拟语气在同位语从句和表语从句中的运用.
\x09作表示建议、要求、命令等的名词advise、idea、order、demand、plan、proposal、suggestion、request等的表语从句和同位语从句,从句中的谓语动词用“（should） + 动词原形”.如：
\x09His suggestion that we (should)go to Shanghai is wonderful.
\x09My idea is that they (should)pay 100 dollars.
\x09（3）虚拟语气在主语从句中的运用.
\x09在主语从句中,谓语动词的虚拟语气用“should + 动词原形”的结构,表示惊奇、不相信、理应如此等.如：
\x09It is necessary(important, natural, strange, etc.)that we should clean the room every day.
\x09It was a pity (a shame, no wonder, etc.)that you should be so careless.
\x09It will be desired(suggested, decided, ordered, requested, proposed, etc.)that she should finish her homework this afternoon.
\x09注意：这种从句表示的是事实.如果说人对这种事实表现出惊奇的情感,就可用虚拟语气.反之,如果不表示惊奇等情感,that从句也可用陈述句语气.如：
\x09It is pity that you can’t swim.
\x093、虚拟语气在其他场合的运用
\x09（1）虚拟语气在as if/as though、even if/even though等引导的表语从句或状语从句中,如果从句表示的动作发生在过去,用过去完成时；指现在状况,则用一般过去时；指将来状况则用过去将来时.如：
\x09He did it as if he were an expert.
\x09Even if she were here, she could not solve the problem.
\x09（2）虚拟语气用于定语从句中.
\x09这种从句常用于句型“It is (high)time (that) … ”中,定语从句的谓语动词用一般过去时(be用were)或should + 动词原形,意思是“(现在)该……”.如：
\x09It’s time that I picked up my daughter.
\x09It’s high time we were going.
\x09（3）虚拟语气用在if only引导的感叹句中.如：
\x09If only I were a bird.
\x09If only I had taken his advice.
\x09（4）虚拟语气在一些简单句中的运用.
\x09①情态动词的过去式用于现在时态时,表示说话人谦虚、客气、有礼貌或语气委婉,常出现在日常会话中.如：
\x09It would be better for you not to stay up too late.
\x09Would you be kind enough to close the door?
\x09②用于一些习惯表达法中.如：
\x09Would you like a cup of tea?
\x09I would rather not tell you.