wether引导的是宾语从句.鉴定是什么从句只要考虑从句所在的位置作为句中的何种成分即可.I'm not sure (wether he will come back soon ）?,由wether引导的从句作宾语成分,是确定的某种内容.如：I don't know (how to spell these words) .由how引导的也是宾语从句,充当的是know的宾语.