The news has spread all over the country ___ the spaceship succeeded in returning to the earth为什么空里添that

_that__ the spaceship succeeded in returning to the earth是一个同位语从句，修饰the news，是news的具体内容。that虽不作句子成分，但不能省略
又如：News came that no language but German could be taught in the two cities.
主语是news
谓语是came
that no language but German could be taught in the two cities是同位语从句

句子主干是The news has spread all over the country
that引导的是news的同位语从句