表语从句讲解及专项练习概念： 表语从句是在复合句中作表语的名词性从句。放在系动词之后,一般结构是“主语+系动词+表语从句”可以接表语从句的连系动词有be, look, remain, seem等。 The trouble is that we are short of money.困难是我们资金短缺。 That is why stone walls are used instead of fences around New England fields.这就是为什么在新英格兰用石头墙而不用栅栏的原因。 At that time, it seemed as if I couldnt think of the right word anyhow.当时,我似乎怎么也想不出一个恰当的字眼来。 引导表语从句的词：从属连词that、whether、as though、 as if（That引导表语从句时，在口语中，间或可以省略。）关系代词who, what, which, whom, whose, whatever, whoever
