whether 是否 是連接詞 引導名詞子句 可與 or not 並用.
whether 引導的子句在句中可作主詞或受詞.
例:
1. Whether he will come (or not) is not known yet.
2. I don't know whether he will come (or not).
whether子句作動詞的受詞時皆可用 if 取代,此時多不與or not 並用
I don't know if he will come.