表语从句就是用一个 句子作为表语.说明主语是什么或者怎么样,由名词,形容词或相当于名词或形容词的词或短语充当,和连系动词一起构成谓语.
连接表语从句的连接词有：that,what,who,when,where,which,why,whether,how,whoever,whomever,whichever ,whatever等.还有如because,as if,as though等.
He has become what he wanted to be ten years ago.
His suggestion is that we should stay calm.
他的建议是,我们应该保持冷静.