however 常用于表示转折或对比，译为“然而”、“可是”，“不过”，“仍然”等时，有的词书认为它是连词，有的词书认为它是副词。之所以将其视为副词，也许是因为像许多副词一样不仅能位于句首，而且能位于句中，甚至句末，相当于 nevertheless 或 despite this.
一、however 可以置于句首，以逗号隔开，译为“然而、可是、仍然”等，例如：
He was feeling very ill. However, he went to school.
他感到很不舒服。但他仍然去上学了。
She is the best student in school. However, she doesn’t do homeworks on time.
她是学校里最好的学生。可是她没有按时做家庭作业。
二、however 还可以出现在主语或 be 动词之后，或实义动词之前，前后以逗号隔开，例如：
Many problems, however, escape detection.
然而许多问题却未被察觉。
We had a small drop in sales last month. We are, however, still above the plan.
上个月我们的销售额略有下降。然而，我们仍高于计划。
They do, however, share a mutual interest in design.
不过他们确实都对设计感兴趣。
三、当 however 用于连接两个独立的句子，应在 however 前面加分号“;”，或另起新句，例如：
I'd like to go with you; however, my hands are full.
我很想和你一块儿去，可是我忙不过来。
解析：此句等于 I'd like to go with you. However, my hands are full.
It’s raining hard; however, I think we should go out.
雨下得很大，但我想我们还得出去。
解析：此句等于 It’s raining hard. However, I think we should go out.
四、在非正式写作中，however 还可以放在句尾，前面以逗号隔开，例如：
Laptop sales surpassed tablet sales in the last year. Mobile phones still remain the highest selling gadget, however.
去年，笔记本电脑的销量超过了平板电脑。然而，手机仍然是最畅销的电子产品。
五、虽然 however 可以以特殊的方式连接两个独立的句子，但不能被当作连词用，例如：
I was offered a promotion at the end of March, however I turned it down. I didn’t want the extra responsibility for a small pay increase.
三月底有人给我升职，但我拒绝了。我不想因为一点点加薪而承担额外的责任。
解析：以上不能用 however，此时只能用 but，正确的是：
I was offered a promotion at the end of March, but I turned it down. I didn’t want the extra responsibility for a small pay increase.
三月底有人给我升职，但我拒绝了。我不想因为一点点加薪而承担额外的责任。
We invited 100 customers to the presentation however only about 50 came.
我们邀请了100位顾客来参加演示，但只有大约50位顾客来了。
解析：以上不能用 however，此时只能用 but 或 however 特殊的连接独立句子的方式。
六、however 与副词或形容词连用，译为“无论到什么程度，不管多么”，例如：
1. however good/well/bad/badly/hard 等
She would still love him however badly he behaved.
不管他行为多么恶劣，她仍然爱他。
If you take money from the fund, however small the amount, you must record it in this book.
如果你从基金里取钱，不管数额多小，你必须把它记在这本书里。
However carefully I explained, she still didn't understand.
无论我解释得多么仔细，她还是没弄懂。
2. however much/many
We’re determined to have a wonderful holiday, however much it costs.
不管花多少钱，我们决心过一个愉快的假期。
However many times you explain things, you can never get him to understand.
不管你解释了多少次，你永远无法让他明白。
3. however long something takes
We are determined to solve this problem, however long it takes.
不管需要多长时间，我们决心解决这个问题。
七、however 译为”不管怎样，无论如何“，例如：
We let the kids decorate their rooms however they want to.
我们让孩子们随心所欲地装饰他们的房间。
However you look at it, this is very worrying news.
不管你怎么看，这是一个非常令人担忧的消息。
关注外语行天下，后期会更精彩。
