是介詞,whether,主要用作為連詞、介詞,例如:
1、Whether we need more food depends on how many people turn up.我們是否需要更多的食物,這要視到場人數而定。
2、I asked whether they could change my ticket.我問他們是否可以給我換票。
3、I'm not sure whether I should tell you this.我拿不準該不該把這事告訴你。