The existence of the giant clouds was virtually required for the Big Bang, first put forward in the 1920s, to maintain its reign as the dominant explanation of the cosmos.(1998年第72题)
注意该句子中的to maintain its reign和前面的for the Big Band是一体的,它们构成了不定式的复合结构for... to do...,插入语first put forward in the 1920s将它从中间分离开来,翻译的时候要注意恢复它们的一体性,即"(使)大爆炸论得以保持其主导地位"。