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:
What feature of airports was significantly increased in length to deal with the increase in jet aircraft traffic?, Context: Airport construction boomed during the 1960s with the increase in jet aircraft traffic. Runways were extended out to 3,000 m (9,800 ft). The fields were constructed out of reinforced concrete using a slip-form machine that produces a continual slab with no disruptions along the length. The early 1960s also saw the introduction of jet bridge systems to modern airport terminals, an innovation which eliminated outdoor passenger boarding. These systems became commonplace in the United States by the 1970s.
answer:
Runways


question:
What did the principle of inertia do for general relativity?, Context: The concept of inertia can be further generalized to explain the tendency of objects to continue in many different forms of constant motion, even those that are not strictly constant velocity. The rotational inertia of planet Earth is what fixes the constancy of the length of a day and the length of a year. Albert Einstein extended the principle of inertia further when he explained that reference frames subject to constant acceleration, such as those free-falling toward a gravitating object, were physically equivalent to inertial reference frames. This is why, for example, astronauts experience weightlessness when in free-fall orbit around the Earth, and why Newton's Laws of Motion are more easily discernible in such environments. If an astronaut places an object with mass in mid-air next to himself, it will remain stationary with respect to the astronaut due to its inertia. This is the same thing that would occur if the astronaut and the object were in intergalactic space with no net force of gravity acting on their shared reference frame. This principle of equivalence was one of the foundational underpinnings for the development of the general theory of relativity.
answer:
one of the foundational underpinnings


question:
When could you watch arena football, Context: From the 1987 season until the late 1990s, the most exposure the league would receive was on ESPN, which aired tape-delayed games, often well after midnight, and often edited to match the alloted time slot. The league received its first taste of wide exposure in 1998, when Arena Bowl XII was televised nationally as part of ABC's old Wide World of Sports.
answer:

after midnight