Answer:
In other words, it is so old that it is difficult to imagine.
Explanation:
In this case, the simplest answer is the correct one. It's not about math or science; it's just what it is; the history of the universe is very hard to imagine because is humans haven't been in it for very long.
Answer:
These words or phrases relate nouns or pronouns toother words in a sentence, and often indicate some sort of positional relationship. ... A phrase acts collectively as a single part of speech, and is usually a noun, adject or adverb.
