Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Pangaea began breaking apart 250 million years ago.
How many millions of years ago did pangaea begin breaking apart?

In their processes of gene expression, archael cells seukaryotic similarties to both bacterial cells and which other type of cell.
In their processes of gene expression, archael cells show similarties to both bacterial cells and which other type of cell?

Volume is a measure of the amount of space that a substance or an object occupies.

What is a measure of the amount of space that a substance or an object occupies?