Question

use of a jack stand
always place a jack stand(s) under a lifted - up vehicle. the jack stand takes the vehicle load, if the jack fails to support the vehicle. this protects the person working on the vehicle from being injured.
check to ensure the floor is suitable to use a jack and stands. the floor should be level and firm; so the risk of the vehicle falling or sinking is minimal.
position the jack stand under a load bearing part of the chassis. neglecting this might cause the cup of the jack stand to damage the vehicle; as well as cause the vehicle to be unstable.
if the suitability of a jacking/support point is in question, consult the vehicle service information.
for what reason is the jack stand always positioned under a load bearing, solid part of the vehicle?
an unsuitable support point damages the jack stand.
supporting a vehicle at a weak support point does not offer the required stability.
the jack stand cup can easily damage an unsuitable part of the vehicle.

Explanation:

The text states that neglecting to position the jack - stand under a load - bearing part of the chassis can cause the cup of the jack - stand to damage the vehicle and make the vehicle unstable. So, supporting at a weak point won't offer required stability and an unsuitable part of the vehicle can be damaged by the jack - stand cup.

Answer:

Supporting a vehicle at a weak support point does not offer the required stability.
The jack stand cup can easily damage an unsuitable part of the vehicle.