What are two types of wood used for shoring that absorb water and expand?

The two types of wood used for shoring that absorb water and expand are Douglas fir and Yellow pine. Both of these woods are known for their structural qualities and are commonly utilized in construction and shoring projects.

Douglas fir is a strong, stable wood that performs well under various conditions, including exposure to moisture, which can lead to expansion. Yellow pine, similarly, is a durable wood that holds up well when in contact with water, also leading to an expansion in size.

In construction, the ability of these woods to absorb water and expand can be advantageous, as it allows for adaptability in changing environmental conditions, ensuring stability and support when needed. The other choices, while they may possess other desirable properties, do not fit the specific criteria of absorbing water and expanding to the same extent as Douglas fir and Yellow pine.