CONJ-SUBORD
(表示选择或怀疑)是否，是不是
You use whether when you are talking about a choice or doubt between two or more alternatives.
例句
To this day, it's unclear whether he shot himself or was murdered...
至今尚不清楚他究竟是饮弹自杀还是被谋杀。
Whether it turns out to be a good idea or a bad idea, we'll find out...
它到底是个好主意还是坏主意我们很快会见分晓。