Therefore的用法 , 一、整句中时一般不放句末，句首后要有逗号，句中1、按一般副词使用2、做插入语（这两个分得清吧） 、Therefore，we must learn English well. 2、They therefore can learn English well. 3、Many fast food restaurant ,therefore,have red furniture or walls. 二、用在分句中，即一个句子一部分表示原因一部分表示结果。 这时一般词前要用分号，其后用不用逗号无所谓。若第二个分句前是逗号或无符号，则要注意therefore是副词，和so不一样，要保持句子完整，应用and therefore。 、I had a headache;therefore I could not go to your party. 2、I was ill,and therefore could not come. 3、These birds are very beautiful and therefore liked by many people. However的用发 1. 用作副词 (1) 表示让步：意为“无论如何”“不管怎样”，用来修饰形容词或副词， 其词序为：however+形容词或副词+主语+谓语。这样用的however其实具有连词的功能，用以引导让步状语从句。如： however much he eats, he never gets fat. 不管他吃多少，他永远吃不胖。 用于此用法时，请注意以下几点： ①此用法属however所有用法中最重要的考点，同学们务请引起高度重视。 ②这样用的 however 与 no matter how 大致同义。如： People always want more, however [no matter how] rich they are. 人总是富了还想再富。 however [No matter how] hard I worked, she was never satisfied. 无论我多么努力地工作，她从来没满意过。 ③有时从句谓语可用情态动词。如： Don’t laugh, however funny it may be. 无论多么有趣也不要笑。 : I’ll try to finish it in time, however hard it may be. 无论多么难，我也要按时完成。 ④“however＋形容词或副词＋主语＋谓语”有时可以有所省略。如： I refuse, however favorable the conditions. 不管条件如何有利，我都不干。(conditions后省去了are) I’d rather have a room of my own, however small (it is), than share a room. 无论房间多么小，我宁愿一个人住一间，而不愿意与别人合住一个房间。 A grammar rule, however true (it is), is useless unless it can be understood. 一条语法规则，不管如何正确，除非能懂，否则毫无用处。 (2) 表示转折：尤其用于谈及一个既成事实时，表示转折，其意为“可是”“仍然”等。可放在句首、句中或句末，通常用逗号与句子其他成分隔开。如： My father, however, did not agree. 但是，我父亲不同意。 | My room is small; however, it’s comfortable. 我的房间很小，但却很舒服。 He said that it was so; he was mistaken, however. 他说情况如此，可是他错了。 注：however不能像 but(但是)那样直接连接两个句子(注意正句中的标点符号)。如： 我们都已尽了最大的努力，不过我们还是输了。. 正：We all tried our best, but we lost the game. 正：We all tried our best; however, we lost the game. 正：We all tried our best. however, we lost the game. (3) 表示惊奇或强调：相当于how ever的用法，其意为“究竟怎样，到底以什么方式”。如： however did you get here without a car 没有汽车你究竟是怎样来的呢 But的用法 but是转折，带有非常浅的转折和递进义在里面，以至于几乎可以省略，或者使用while替代 首句描述母亲动作，次句是人物的状态 首句正常描述，次句揭示问题，引出下文。文学作品里的词语活用很常见，不用钻牛角尖 ~ 本文来源：https://www.wddqw.com/doc/953f8f48c9aedd3383c4bb4cf7ec4afe04a1b1b2.html