but是连词,表示（较强的）转折,连接两个句子时只用加逗号.例如：I love her,but she doesn't love me.
however是副词,也表示（较强的)转折,但连接两个句子时要用分号,而且在这个词后还要加逗号.例如：I love her; however,she doesn't love me.或者将两句子分开写.例如：I love her.However,she doesn't love me.
while作连词使用时,表示（较弱的）转折,连接两个句子时用逗号,但两个句子的主语不一样.例如:I like singing,while my sister likes dancing.
yet作连词使用时,也表示（较弱的）转折,连接两个句子时也用逗号,但两个句子的主语是一样的.例如：He has a good job,yet he never seems o have any money.