instruction:
In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
question:
An object that is fixed in place and cannot move is said to be also what?, Context: The normal force is due to repulsive forces of interaction between atoms at close contact. When their electron clouds overlap, Pauli repulsion (due to fermionic nature of electrons) follows resulting in the force that acts in a direction normal to the surface interface between two objects.:93 The normal force, for example, is responsible for the structural integrity of tables and floors as well as being the force that responds whenever an external force pushes on a solid object. An example of the normal force in action is the impact force on an object crashing into an immobile surface.
answer:
immobile


question:
What does the S in "PBS" stand for?, Context: New York is also a major center for non-commercial educational media. The oldest public-access television channel in the United States is the Manhattan Neighborhood Network, founded in 1971. WNET is the city's major public television station and a primary source of national Public Broadcasting Service (PBS) television programming. WNYC, a public radio station owned by the city until 1997, has the largest public radio audience in the United States.
answer:
Service


question:
What can a tree produce after it is mature?, Context: Different pieces of wood cut from a large tree may differ decidedly, particularly if the tree is big and mature. In some trees, the wood laid on late in the life of a tree is softer, lighter, weaker, and more even-textured than that produced earlier, but in other trees, the reverse applies. This may or may not correspond to heartwood and sapwood. In a large log the sapwood, because of the time in the life of the tree when it was grown, may be inferior in hardness, strength, and toughness to equally sound heartwood from the same log. In a smaller tree, the reverse may be true.
answer:

wood