Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
The fluid in the coelomata contains coelomocyte cells that defend the animals against parasites and infections. In some species coelomocytes may also contain a respiratory pigment – red hemoglobin in some species, green chlorocruorin in others (dissolved in the plasma) – and provide oxygen transport within their segments. Respiratory pigment is also dissolved in the blood plasma. Species with well-developed septa generally also have blood vessels running all long their bodies above and below the gut, the upper one carrying blood forwards while the lower one carries it backwards. Networks of capillaries in the body wall and around the gut transfer blood between the main blood vessels and to parts of the segment that need oxygen and nutrients. Both of the major vessels, especially the upper one, can pump blood by contracting. In some annelids the forward end of the upper blood vessel is enlarged with muscles to form a heart, while in the forward ends of many earthworms some of the vessels that connect the upper and lower main vessels function as hearts. Species with poorly developed or no septa generally have no blood vessels and rely on the circulation within the coelom for delivering nutrients and oxygen.
What runs the length of annelids' brains with well-developed septa?
A: unanswerable

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
The role of the gas is to prevent evaporation of the filament, without introducing significant heat losses. For these properties, chemical inertness and high atomic or molecular weight is desirable. The presence of gas molecules knocks the liberated tungsten atoms back to the filament, reducing its evaporation and allowing it to be operated at higher temperature without reducing its life (or, for operating at the same temperature, prolongs the filament life). It however introduces heat losses (and therefore efficiency loss) from the filament, by heat conduction and heat convection.
What does not knock the liberated tungsten atoms back to the filament?
A: unanswerable

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Pesticides are often referred to according to the type of pest they control. Pesticides can also be considered as either biodegradable pesticides, which will be broken down by microbes and other living beings into harmless compounds, or persistent pesticides, which may take months or years before they are broken down: it was the persistence of DDT, for example, which led to its accumulation in the food chain and its killing of birds of prey at the top of the food chain. Another way to think about pesticides is to consider those that are chemical pesticides or are derived from a common source or production method.
How long may it take for persistent pesticides to be broken down?
A: months or years

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The Alps provide lowland Europe with drinking water, irrigation, and hydroelectric power. Although the area is only about 11 percent of the surface area of Europe, the Alps provide up to 90 percent of water to lowland Europe, particularly to arid areas and during the summer months. Cities such as Milan depend on 80 percent of water from Alpine runoff. Water from the rivers is used in over 500 hydroelectricity power plants, generating as much as 2900 kilowatts of electricity.
Water from the rivers is used in over how many hydroelectric power plants?
A:
500