英语的问题同一句转换：They believe that she will win.They ____ _____tha

They believe that she will win.
They __are__ __sure___that she will win
be sure +that 从句

They are going to Japan the day after tomorrow.
they are _leaving____ _for_____Japan the day after tomorrow.
leave for sp. 出发去某个地方,前往某个地方

从句是相对于主句而言的,主、从关系
一个普通的句子,例如 He wants to know the secret.
这个句子主语是he
谓语是 wants to know
宾语是 the secret
也就是sb. wants to know sth.

如果当这个宾语sth.是用一个句子来充当,
那么除了原来的句子,就出现了另外一个句子,这时候就有了主句跟从句的区别
如He wants to know what they are talking about.
主句就是原来的He wants to know sth.
而从句就是后面的一整个句子 what they are talking about.
而且从句一般都要有个引导词来引出来的,这里就是what引导了一个宾语从句

从句的种类分很多种,根据这个从句在整个大的句子当中所充当的成分来判断,而且不同种类的从句引导词也有所不同.

they are planning to Japan the day after tomorrow.
从句其实就是复合句的一部分。就是有连接词的那句

从句就是在一个句子里面添加一个辅助的句子表达意思。

are sure
planning to