In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

[Q]: What is the force of gravity noted as?, Context: Since then, and so far, general relativity has been acknowledged as the theory that best explains gravity. In GR, gravitation is not viewed as a force, but rather, objects moving freely in gravitational fields travel under their own inertia in straight lines through curved space-time – defined as the shortest space-time path between two space-time events. From the perspective of the object, all motion occurs as if there were no gravitation whatsoever. It is only when observing the motion in a global sense that the curvature of space-time can be observed and the force is inferred from the object's curved path. Thus, the straight line path in space-time is seen as a curved line in space, and it is called the ballistic trajectory of the object. For example, a basketball thrown from the ground moves in a parabola, as it is in a uniform gravitational field. Its space-time trajectory (when the extra ct dimension is added) is almost a straight line, slightly curved (with the radius of curvature of the order of few light-years). The time derivative of the changing momentum of the object is what we label as "gravitational force".
[A]: The time derivative of the changing momentum of the object


[Q]: What is fundamental to the function of the airport that has yet to be obtained?, Context: The UK government has spent £250 million in the construction of the island's airport. Expected to be fully operational early 2016, it is expected to help the island towards self-sufficiency and encourage economic development, reducing dependence on British government aid. The airport is also expected to kick start the tourism industry, with up to 30,000 visitors expected annually. As of August, 2015 ticketing was postponed until an airline could be firmly designated.
[A]: airline


[Q]: The organic matter feeds themselves and their hosts, while worms what?, Context: The gut is generally an almost straight tube supported by the mesenteries (vertical partitions within segments), and ends with the anus on the underside of the pygidium. However, in members of the tube-dwelling family Siboglinidae the gut is blocked by a swollen lining that houses symbiotic bacteria, which can make up 15% of the worms' total weight. The bacteria convert inorganic matter – such as hydrogen sulfide and carbon dioxide from hydrothermal vents, or methane from seeps – to organic matter that feeds themselves and their hosts, while the worms extend their palps into the gas flows to absorb the gases needed by the bacteria.
[A]:
extend their palps into the gas flows to absorb the gases needed by the bacteria