Problem: Printed circuit board:

Unpopulated boards are usually bare-board tested for "shorts" and "opens". A short is a connection between two points that should not be connected. An open is a missing connection between points that should be connected. For high-volume production a fixture or a rigid needle adapter is used to make contact with copper lands on the board. Building the adapter is a significant fixed cost and is only economical for high-volume or high-value production. For small or medium volume production flying probe testers are used where test probes are moved over the board by an XY drive to make contact with the copper lands. The CAM system instructs the electrical tester to apply a voltage to each contact point as required and to check that this voltage appears on the appropriate contact points and only on these.

Populated boards are usually what?
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A: unanswerable

Problem: Iranian art encompasses many disciplines, including architecture, painting, weaving, pottery, calligraphy, metalworking, and stonemasonry. The Median and Achaemenid empires left a significant classical art scene which remained as basic influences for the art of the later eras. Art of the Parthians was a mixture of Iranian and Hellenistic artworks, with their main motifs being scenes of royal hunting expeditions and investitures. The Sassanid art played a prominent role in the formation of both European and Asian medieval art, which carried forward to the Islamic world, and much of what later became known as Islamic learning, such as philology, literature, jurisprudence, philosophy, medicine, architecture, and science, were of Sassanid basis.
The Sassanid became a cornerstone of what type of learning?
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Answer: Islamic learning

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Eighty percent of Greece consists of mountains or hills, making the country one of the most mountainous in Europe. Mount Olympus, the mythical abode of the Greek Gods, culminates at Mytikas peak 2,918 metres (9,573 ft), the highest in the country. Western Greece contains a number of lakes and wetlands and is dominated by the Pindus mountain range. The Pindus, a continuation of the Dinaric Alps, reaches a maximum elevation of 2,637 m (8,652 ft) at Mt. Smolikas (the second-highest in Greece) and historically has been a significant barrier to east-west travel.
The tallest mountain in the Pindus range is what?
A: Mt. Smolikas

Context and question: More than half of habitat for listed species is on non-federal property, owned by citizens, states, local governments, tribal governments and private organizations. Before the law was amended in 1982, a listed species could be taken only for scientific or research purposes. The amendment created a permit process to circumvent the take prohibition called a Habitat Conservation Plan or HCP to give incentives to non-federal land managers and private landowners to help protect listed and unlisted species, while allowing economic development that may harm ("take") the species.
When was it decided species could be taken for scientific purposes?
Answer: unanswerable

Question: Important geological concepts were established as naturalists began studying the rock formations of the Alps in the 18th century. In the mid-19th century the now defunct theory of geosynclines was used to explain the presence of "folded" mountain chains but by the mid-20th century the theory of plate tectonics became widely accepted.
Is there an answer to this question: What was used in the mid-19th century to explain the presence of "folded" mountain chains?

Answer: theory of geosynclines

The most precarious of these quake-lakes was the one located in the extremely difficult terrain at Mount Tangjia in Beichuan County, Sichuan, accessible only by foot or air; an Mi-26T heavy lift helicopter belonging to the China Flying Dragon Special Aviation Company was used to bring heavy earthmoving tractors to the affected location. This operation was coupled with the work done by PLAAF Mi-17 helicopters bringing in PLA engineering corps, explosive specialists and other personnel to join 1,200 soldiers who arrived on site by foot. Five tons of fuel to operate the machinery was airlifted to the site, where a sluice was constructed to allow the safe discharge of the bottlenecked water. Downstream, more than 200,000 people were evacuated from Mianyang by June 1 in anticipation of the dam bursting.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): Where was the worst of the quake lakes located?
Ah, so..
Mount Tangjia