Is - two billion dollars is a unit, one unit so it is singular and you use the singular verb
think - scientists is a plural, therefore, you must use the plural verb form of think
Answer:
their common passion for paleontology and mutual disdain for each other fueled their ambition, ultimately leading to the discovery of over a hundred new species in America. At the same time, their bitter rivalry damaged their reputations and left the two almost penniless at their deaths.
Dirt-disappointed means just extremely disappointed and depressed about something, tired of something.
They feel comfortable in their own current positions and only care about privilege if it actually affects/bothers themselves.
The meter used from the poem 'The Aim' was the iambic tetrameter.
