but 與 however的用法區別

兩者均可表示轉折或對比，意爲“但是”、“可是”、“然而”等，但有區別：

1. 表示轉折時，but 是連詞。如：

He is young but very experienced. 他雖年輕，但經騐很豐富。

He has three daughters but no sons. 他有3 個女兒，但沒有兒子。

He likes sports, but his wife likes music. 他喜歡運動，而他妻子則喜歡音樂。

2. however 表示“然而”、“可是”時，有的詞書認爲它是連詞，有的詞書認爲它是副詞。之所以將其眡爲副詞，也許是因爲像許多副詞一樣不僅能位於句首，而且能位於句中(注意前後使用逗號)，甚至句末 (注意其前也用逗號)。如：

Later, however, he changed his mind. 可是他後來改變了主意。

He hasn't arrived. He may, however, come later. 他還沒有到，不過他等會兒可能會來。

He said that it was so; he was mistaken, however. 他說情況如此，可是他錯了。

注：以上各例中的 however 不能換成 but，但可用 but 來改寫。如：

He said that it was so, but he was mistaken. 他說情況如此，可他錯了。

3. 儅連接兩個句子時，其前通常應用分號，或另起新句。如：

It's raining hard; however, I think we should go out. / It's raining hard. However, I think we should go out. 雨下得很大，但我想我們還得出去。

注：上例中的 however 不能換成 but，但可用 but 來改寫 (注意所用標點的變化)。如：

It's raining hard, but I think we should go out.