Answer:
A passage is a few sentences. Do you need help finding it as well?
A primary source. For example, a journal entry, a newspaper article, but they must be written by someone who saw it with their own eyes, rather than a secondary.
Answer:
support (a building or other structure) from below by laying a solid foundation below ground level or by substituting stronger for weaker materials.
Explanation:
This is the general definition of underpin
