倒装句是指将主语和谓语的位置颠倒过来的句子结构。在英语中，倒装句通常用于表达强调或产生一种修辞效果。下面是however在倒装句中的用法：
1、however+主语+动词，作为副词。这种结构表示一种转折关系。例如：
- However cold it is outside, I’ll still go for a run.（不管外面多冷，我仍会去跑步。）
- However much he studies, he never gets good grades.（不管他学习多少，他从来没得过好成绩。）
2、主语+动词+however，作为连词。这种结构也表示转折关系，但语气比较弱。例如：
- I’ll still go for a run, however cold it is outside.（不管外面多么冷，我仍会去跑步。）
- He never gets good grades, however much he studies.（不管他学习多少，他从来没得过好成绩。）
因此，使用however倒装句时，需要在主语和谓语的位置之间加上however，并注意顺序和语态的变化。
“However”常见用法：
1、表示让步关系
当前后两个句子之间存在一点矛盾时，可以用however表示让步关系。例如：
- I tried my best. However, I still failed the test.
- We have done everything we could. However, the result was not as good as we expected.
2、表示转折关系
当前后两个句子之间存在一个明显的转折时，可以用however表示转折关系。例如：
- She can be very kind. However, she can also be very tough when it's needed.
- The children love playing on their phones. However, they still enjoy outdoor activities too.
3、表示对比关系
当两个句子之间存在明显的对比时，可以使用however表示对比关系。例如：
- The company's profit has been increasing every year. However, the CEO's salary has not been adjusted all along.
- The hotel room was quite expensive. However, it was very dirty.
4、表示强调关系
有时候，为了强调某一点，可以使用however表示强调关系。例如：
- The weather is very nice. However, we still have to finish our work.
- You may be the boss. However, that does not mean you are always right.
总之，“however”可以让你的语言更加生动、准确、丰富。但需要注意的是，它更多是用于正式、严肃、商务场合。在口语、日常生活交流等场合中，不需要总去使用这个词。