but和however的区别

1. however作副词用时，表示“然而；但是”，可以位于句首、句中和句末；位于句首时，要用逗号与句子其它部分隔开；位于句中时，其前后都要用逗号；位于句末时其前用逗号分开。 例如: She felt ill. She went to work, however, and tried to concentrate. 她病了。然而她照旧去上班，并且尽力集中精神工作。 His first response was to say no. Later, however, he changed his