The first advance led to ____________ ___________ plants, such as those that were ubiquitous in the great coal-forming swamps of the Carboniferous.
(The first advance; led; to ____________ ___________ plants, such as those) (those; were; ubiquitous; L:in the great coal-forming swamps of the Carboniferous)
The first advance those
led were
to ____________ ___________ plants, such as those
ubiquitous L:in the great coal-forming swamps of the Carboniferous