however的用法和位置详细解析如下：

一、概述

如果你的朋友邀请你吃完饭，你不想去。你说：“我很喜欢你做的菜。可是我已经有约了。”这个时候，就可以用however表示“可是”，用于引出与前文相反、形成对比的表达。

二、用法详解

1.however  adv. 然而、可是

   I love your cooking. However, I already have plans for dinner tonight.

我喜欢你做的菜。然而，我今晚晚餐已经有计划了。

   The forecast is good. However,it’s possible that it will rain later.

天气预报情况挺好的。然而，有可能稍后会下雨。

2. however可在句首句中句末，常有逗号隔开

 She is not well. However, she can still walk.

 她不太舒服。然而，她仍能行走。

注意在句中时，however的前后都有逗号。

Later, however, he came back.

可是后来他回来了。 

The service is bad. The food, however, tastes good.

服务不好。然而，食物挺美味的。

He is honest, however.

 然而他是诚实的。

 Not everyone likes her song, however.

然而，并不是所有人都喜欢她的歌曲。

3.拓展：however有另一种用法，表示“无论如何”“不管怎样”相当于no matter how。

 However hard she tried, she couldn’t persuade him.

不管她如何尝试，她都无法说服他。

We have to finish our work, however long it takes.

我们必须完成工作，不管花费多长时间。

以上就是however的用法和位置的详细解析，你可能还需要查看链接：however和but的区别