我们在学习英文的语法知识的时候，有时候会将差不多的词搞混，例如：however和whereas，知道however和whereas语法吗？
e.g. “The historical evidence appears to suggest a clear-cut situation. On the other hand, the archaeological evidence presents a somewhat less straightforward picture of what happened that day.”
那天发生的事在历史证据显示一个清楚的状况。但另一方面，考古证据却显示一个较不容易理解的局面。
e.g. “Scholar A’s opinion, then, is based on insufficient evidence. By contrast, Scholar B’s opinion seems more plausible.”
学者A的意见是根据较不完整的资料。相较之下，学者B的意见可信度较高。
(属副词兼作并列连词用，表转折比but稍松弛，可位于句中首、尾用，逗号分开)
例：I told him it was no meaning. However, he didn't listen to me.
我告诉了他这样做没有意义，但是他没有听我的。
but
however
while
though, or
otherwise
on the contrary
on the other
hand, in contrast
despite
in spite of
even though
except (for)
instead
of course
after all
e.g. “Writer A asserts that this was the reason for what happened. Then again, it’s possible that he was being paid to say this.”
A作者断言这个事件发生的原因，但话说回来，也有可能是有人付钱叫他这么说的。
e.g. We could go to the Indian restaurant, or alternatively, we could try that new Italian place.
我们可以去那家印度餐馆，或者也可以到那家新开的意大利餐馆尝尝。
例：When I look at her new shoes, mine seems old-fashioned by contrast.
看到她的新鞋子，我的鞋子相较之下就过时了。
mine指代我的鞋子。
(属并列连词表转折，上下分句所述情况相反，用在句中，后不加逗号)
例：The building got fire,but the man rush into it.
这栋大楼着火了，但是这个男的仍然冲了进去。
but肯定是最常用的一个了。
(属并列连词表对比，但程度不及st诅l强烈)
例：He is a nice guy, while he is not a good husband.
他是个很好的人，然而他不是一个好丈夫。
要注意，while最初一开始学得时候，老师一般只会教“当”的意思，但是while也有然而表示转折的意思，而且一定是链接两个句子。
▼1. 用作副词，注意以下用法：
(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，用以引导一个让步状语从句。如：
However much he eats, he never gets fat. 不管他吃多少，他永远吃不胖。
However cold it is, he always goes swimming. 不管天有多冷，他都去游泳。
However far it is, I intend to drive there tonight. 不管有多远，我今晚也要开车到那儿去。
这样用的 however 与 no matter how 大致同义。如：
No matter how much he eats, he never gets fat.
No matter how cold it is, he always goes swimming.
No matter how far it is, I intend to drive there tonight.
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。
另外，“however+形容词或副词+主语+谓语”有时可以有所省略。如：
I refuse, however favourable 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。
注意，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。
误：We all tried our best, however we lost the game.
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？
However does he manage to write music when he is so deaf? 他聋成这个样子，究竟是怎样从事作曲的呢？
▼2. 用作连词，引导方式状语从句，表示“无论以何种方式”“不管怎样”。如：
However it may be, I shall take your word. 无论如何，我将会相信你的话。
The painting looks wrong however you look at it. 这张画不论怎么看都显得不对劲。
However you travel, it’ll take you at least two days. 无论你怎么个走法，至少要两天时间。
e.g. Differ from his position, she claims that this plan still has a lot of flaws.
不同于他的立场，她觉得这个计划还是有很多的瑕疵。
例：The food sells smelly,whereas it tastes well.
这个食物闻着臭，但是吃起来很不错。
However和whereas的用法不同。请遵守下面的规则，以避免错误。
Use 'however' (followed by a comma) at the beginning of a sentence to contrast with the previous sentence:
在句首使用however(后面要加逗号)来表示和前一句意思相反。
Some people believe that schools are responsible for the behaviour of their students. However, others argue that discipline is the responsibility of parents.
Use 'whereas' (after a comma) to contrast two ideas in the same sentence:
Whereas用于同一句内的两个相反意见(前面要加逗号)。
Some people believe that schools are responsible for the behaviour of their students, whereas others argue that discipline is the responsibility of parents.
You can use 'on the other hand' or 'by contrast' in the same way as 'however'. You can use 'while' instead of 'whereas'.
On the other hand和by contrast的用法和however相同，而while和whereas的用法一样。
例：Sometimes he is impolite,but he is a nice guy for all that.
他有时不太礼貌，但还是个好人。
例： she apologized for the clothes, even so I didn't accapt it.
尽管�
▼连接词 conj.
1.(用以比较或对比两个事实)但是，然而，尽管
Some praise him,whereas others condemn him.
有些人赞扬他，而有些人谴责他。
2.(用于正式文件中句子的开头)鉴于 (法律用语)
▼名词 n.
以“whereas”开头的公文
1."And","but"and"whereas" are conjunctions.and,but和whereas是连词。
2.Some of the studies show positive results,whereas others do not.有一些研究结果令人满意，然而其他的则不然。
3.They want a house,whereas we would rather live in a flat.他们想要一座房子，而我们宁愿住在一套房间里。
4.Some praise him,whereas others condemn him.有些人赞扬他，而有些人谴责他。
5.Whereas I was blind,now I see.我过去双目失明，现在则重见天日。
c.Materialists face truth,whereas idealists shun it.唯物主义者面向真理，唯心主义者则逃避真理。
7.Religion is a diffuse topic liable to unending disputation whereas theism is not.宗教是一个容易引起无休止争论的弥散型话题，而有神论则不是。
8.Whereas the medical doctors' wives don't flop--catch 'em at it!而医生的老婆却不用祷告——你见过她们祷告么！
Pensions are linked to inflation,whereas they should be linked to the cost of living.养老金与通货膨胀挂钩，然而它们其实应该和生活费用挂钩。
10.Some people praise him,whereas others condemn him.有些人赞扬他，而有些人谴责他。
例：Even though/if she got high score in the exam,she still need good evaluation to get into university.
虽然她的分数很高，但是她仍然需要一个好的评估才能进入大学。
例： The office is hot.In spite of that,he has been staying office for 3 hours.
办公室很热，尽管如此，他还是在里面呆了3小时。
that是指代前一句。
e.g. Learning a language is not merely about memorizing vocabulary. Instead, it has many aspects to be paid attention to.
学一个语言不仅仅在于背单词。还有很多方面我们必须要注意。
(属副词作并列连词用，语气比but强烈，可与与and，but连用)
例：I didn't give his present yet.
我还没有把礼物给他。
yet一般都是放在句尾的，而且只出现在否定句中。
e.g. He forgets most things, but having said that, he always remembers my birthday.他很健忘，不过，他一直记得我的生日。
例：He didn't go over the exam,nevertheless he passed it.
他没有复习考试，但是他通过了。
While和whilst一样，但whilst要更正式些(一本著名的语法书这么说的)。
Whereas is always used for contrast. While/whilst can be used for contrast, or to mean "at the same time".
Whereas总是用于表示相反的意见。While和whilst既可以表示意思相反，也可以表示“与此同时”。
As can mean "because" or "exactly at the moment when".
As可以表示“因为”，也可以指“就在那时”。
例：His face was serious, but nonetheless very friendly.
他脸上表现得很严肃，然而是个很和善的人。
e.g. He's overweight and bald, (and) yet somehow, he's attractive.他肥胖且秃头，然而不知为何却很有魅力。
yet解释为然而时，通常放句中，前后面皆需要逗号。
(属副词作连词用)尽管如此，但仍然如故(常用于后一分句，可以跟逗号)
例：It's a sunny day.Still, we have to stay home.
今天天气真好，但是我们得呆在家里做作业。
e.g. She walked home by herself although she knew that it was dangerous.
她一个人步行回家，尽管她知道那样做很危险。
However可单独成句，通常放在句首，后面紧接着逗号。
However, he isn’t qualified enough for the job.
however亦可以夹在两个子句中，前方需分号，后方为逗号。
This seems to be a fair way; however, we still should carefully consider every aspect.
例：I have never been an enemy of snacks; on the contrary, I consider snacks could be healthy.
我从来不反对吃零食；正相反，我认为零食也可以吃的很健康。