主语从句的特点是以句子的形式或结构在句中充当主语成分。它的表现形式通常是由从属连词(如that,whether)、连接代词(如who,whom,whose,what,which等)或连接副词(如when,where,why,how等)引出。值得注意的是,从属连词that只用来引出主语从句,它在从句中不担任任何成分,本身也无实际意义。whether在句中虽不担任任何成分,但是它本身有词义,表示“是否”的意思。其他连接代词或连接副词,除引出主语从句外,还在从句中担任某 The subject clause is characterized by the form or structure of the sentence as the subject component in the sentence. Its form of expression is usually derived from subordinate conjunctions (such as that, whether), connection pronouns (such as who, who, who, what, which, etc.) or connective adverbs (such as when, where, why, how, etc.). It is worth noting that the subordinate conjunction that is used only to elicit the subject clause. It does not hold any component in the clause and has no practical significance in itself. Whether or not in the sentence does not constitute any element, but it has its own meaning, meaning “yes”. Other connection pronouns or connective adverbs, in addition to quoting the subject clause, also serve as a clause