Context and question: The U.S., UK, France, Italy and the majority of other Western countries considered the annexation of Estonia by the USSR illegal. They retained diplomatic relations with the representatives of the independent Republic of Estonia, never de jure recognised the existence of the Estonian SSR, and never recognised Estonia as a legal constituent part of the Soviet Union. Estonia's return to independence became possible as the Soviet Union faced internal regime challenges, loosening its hold on the outer empire. As the 1980s progressed, a movement for Estonian autonomy started. In the initial period of 1987–1989, this was partially for more economic independence, but as the Soviet Union weakened and it became increasingly obvious that nothing short of full independence would do, Estonia began a course towards self-determination.
What institution did Western countries refuse to recognize?
Answer: the Estonian SSR
Context and question: There are many styles of mandolin, but four are common, the Neapolitan or round-backed mandolin, the carved-top mandolin and the flat-backed mandolin. The round-back has a deep bottom, constructed of strips of wood, glued together into a bowl. The carved-top or arch-top mandolin has a much shallower, arched back, and an arched top—both carved out of wood. The flat-backed mandolin uses thin sheets of wood for the body, braced on the inside for strength in a similar manner to a guitar. Each style of instrument has its own sound quality and is associated with particular forms of music. Neapolitan mandolins feature prominently in European classical music and traditional music. Carved-top instruments are common in American folk music and bluegrass music. Flat-backed instruments are commonly used in Irish, British and Brazilian folk music. Some modern Brazilian instruments feature an extra fifth course tuned a fifth lower than the standard fourth course.
Which form of music do Neapolitan mandolins feature? 
Answer: European classical music and traditional music.
Context and question: Annelids with blood vessels use metanephridia to remove soluble waste products, while those without use protonephridia. Both of these systems use a two-stage filtration process, in which fluid and waste products are first extracted and these are filtered again to re-absorb any re-usable materials while dumping toxic and spent materials as urine. The difference is that protonephridia combine both filtration stages in the same organ, while metanephridia perform only the second filtration and rely on other mechanisms for the first – in annelids special filter cells in the walls of the blood vessels let fluids and other small molecules pass into the coelomic fluid, where it circulates to the metanephridia. In annelids the points at which fluid enters the protonephridia or metanephridia are on the forward side of a septum while the second-stage filter and the nephridiopore (exit opening in the body wall) are in the following segment. As a result, the hindmost segment (before the growth zone and pygidium) has no structure that extracts its wastes, as there is no following segment to filter and discharge them, while the first segment contains an extraction structure that passes wastes to the second, but does not contain the structures that re-filter and discharge urine.
How many stages are there in annelids' waste filtration?
Answer:
two