从句中一般作主语或宾语(指物时还可以用which代替),并且作宾语时常常省略.that在同位语从句中仅起连接作用,不充当任何成分,并且不能省略,也不能用which来代替.如: 3．The order that we should send a few people to help the other groups was received yesterday. 我们应派几个人去帮别的几个小组的命令昨天收到了. (同位语从句,是对order的具体解释,that虽不作成分,但不能省略..) 4．The order that we received yesterday was that we should send a few people to help the other groups. 我们昨天收到的命令是我们应该派几个人去帮助别的几个小组. (定语从句,是名词order的修饰语,that在从句中作received的宾语,可以省略.)
