but 口语常用词，语气较强，泛指与前述情况相反。
however 表转折关系，语气稍弱于but，连接性也弱一些，因而常作插入语。
still 语气强，多用于肯定句或疑问句。指尽管作出让步，采取措施或表示反对，但情况仍然如故，无所改变。
yet 常用于否定句，语气比still稍强。指不管作出多大努力或让步，仍达不到预期的结果。
nevertheless 指尽管作出完全让步，也不会发生任何影响。
while 表对比，一般可与whereas换用，但程度弱一些。
whereas 表对比，一般可与while互换。
参考例句
1. At first he insisted on the accuracy of his account, however, he agreed with what I said. 一开始他坚持他的说法准确，可他还是同意了我的论点。
2. However, such a seduction is not love. 然而，这样一种诱惑并不是爱。
3. However, I still only forever love you. 无论如何，我仍旧只永远爱你。
英英解释
adv.
1. despite anything to the contrary (usually following a concession)
2. by contrast; on the other hand
3. to whatever degree or extent
4. in whatever way or manner
