我一般是看主句缺什么成分或者关系代作的成分,例如：
He told me that he would go to the college the next year .
that后面是引导的从句,he told me 是主句,"he told me" 译为"他告诉我".他告诉我的内容就是宾补（主+谓+宾+宾补),所以是宾语从句.
我解释不到,反正你多读书培养语感,让老师给你讲吧!