However 可以表示“然而”或“尽管如此”，引出与前文相反或对前文有所限制的观点。它比 but 更正式，常见于作文和工作邮件。若后面直接接形容词或副词，不加逗号，还可以表示“无论多么”：however hard I try。
你会怎样使用 however？
写一句英语，检查连接词与意思是否匹配，并查看修改建议。
本次检查比平时稍久，完成后反馈会自动显示在这里。
Sentence. However, + sentence; clause; however, + clause; subject, however, + verb; however + adjective/adverb + clause
- Public transport reduces traffic in city centres. However, many rural areas still lack regular bus services.
- Online learning is flexible; however, it requires a high level of self-discipline.
- However hard I try, I can't remember people's names at parties.
修改原因
修改前The course is cheap, however it takes a lot of time.
修改后The course is cheap; however, it takes a lot of time.
连接这里两个独立句子时，however 不能像 but 那样只靠前面的一个逗号。可以在它前面用句号或分号，并在它后面加逗号：cheap; however, it takes。
But 可以连接同一句中的两个分句，后面不需要逗号：The course is cheap, but it takes a lot of time。这里换成 however 时，要另起一句或先用分号，后面再加逗号。如果 however 后没有逗号而是直接接形容词，含义又不同：However tired I am, I read a few pages before bed。
动手练习
Most students liked the new timetable, ___ some teachers found it inconvenient.
查看答案
but — 题目中的两个分句只由逗号隔开，空格后也没有逗号，符合 but 的连接方式。However 不能直接填入；若要使用，需要改成 timetable; however, some teachers。
用两句话写一项你所在城市、公司或大学新设的规则或限制。第一句说明为什么设立，第二句以 However 开头，说明出现了什么问题。
Our city banned cars from the old town to reduce air pollution. However, traffic on the surrounding streets has become much heavier.
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