【doubt】doubtthat...和doubtif/whether用法有啥区别?举个例子

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【答案】 楼主,你好doubt if 或that的用法1. doubt如果是动词引导宾语从句时,如果主句是肯定句,则宾语从句的引导词可用if/whether.
　　如：I doubt if/whether he is a student.
　　当然,如果此宾语从句中含有or/or not时,只能使用whether.
　　如：I doubt whether he is a student or not.
　　I doubt whether he is a student or a teacher.
　　另：doubt如果是动词引导宾语从句时,如果主句是否定句/疑问句,则宾语从句的引导词只能用that.
　　如：I don't doubt that he is a student.
　　2. doubt如果是名词引导同位语从句时,如果主句是肯定句,则同位语从句的引导词只能用whether.
　　如：I have doubt whether he is a student.
　　doubt如果是名词引导同位语从句时,如果主句是否定句/疑问句,则同位语从句的引导词只能用that.
　　如：There is no doubt that he is a student.望采纳!