That is because…句型

“That is because…”句型中从属连词because引导的名词性从句在此作表语， 这也是个常用句型， 意为“这就是为什么……/因为……”。 例如：

He did not see the film last night. That is because he had to help his little sister with her homework.
昨天晚上他没有去看电影， 那是因为他得帮助他的妹妹做作业。
(第一句话说明结果， 第二句话说明原因)