Problem: Nanjing:

In the past 20 years, several commercial streets have been developed, hence the nightlife has become more diverse: there are shopping malls opening late in the Xinjiekou CBD and Hunan Road. The well-established "Nanjing 1912" district hosts a wide variety of recreational facilities ranging from traditional restaurants and western pubs to dance clubs. There are two major areas where bars are densely located; one is in 1912 block; the other is along Shanghai road and its neighbourhood. Both are popular with international residents of the city.

When did more commercial streets become built in Nanjing?
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A: In the past 20 years


Problem: Heartwood (or duramen) is wood that as a result of a naturally occurring chemical transformation has become more resistant to decay. Heartwood formation occurs spontaneously (it is a genetically programmed process). Once heartwood formation is complete, the heartwood is dead. Some uncertainty still exists as to whether heartwood is truly dead, as it can still chemically react to decay organisms, but only once.
How does heartwood formation occur due to its being genetically programmed?
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Answer: spontaneously


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Circadian rhythms allow organisms to anticipate and prepare for precise and regular environmental changes. They thus enable organisms to best capitalize on environmental resources (e.g. light and food) compared to those that cannot predict such availability. It has therefore been suggested that circadian rhythms put organisms at a selective advantage in evolutionary terms. However, rhythmicity appears to be as important in regulating and coordinating internal metabolic processes, as in coordinating with the environment. This is suggested by the maintenance (heritability) of circadian rhythms in fruit flies after several hundred generations in constant laboratory conditions, as well as in creatures in constant darkness in the wild, and by the experimental elimination of behavioral, but not physiological, circadian rhythms in quail.
What allows organisms to anticipate and prepare for unexpected environmental changes?
A: unanswerable


Context and question: Quotient groups and subgroups together form a way of describing every group by its presentation: any group is the quotient of the free group over the generators of the group, quotiented by the subgroup of relations. The dihedral group D4, for example, can be generated by two elements r and f (for example, r = r1, the right rotation and f = fv the vertical (or any other) reflection), which means that every symmetry of the square is a finite composition of these two symmetries or their inverses. Together with the relations
What groups can be combined to describe every group?
Answer: is the quotient of the free group over the generators of the group


Question: A number of other health conditions occur more frequently in those with asthma, including gastro-esophageal reflux disease (GERD), rhinosinusitis, and obstructive sleep apnea. Psychological disorders are also more common, with anxiety disorders occurring in between 16–52% and mood disorders in 14–41%. However, it is not known if asthma causes psychological problems or if psychological problems lead to asthma. Those with asthma, especially if it is poorly controlled, are at high risk for radiocontrast reactions.
Is there an answer to this question: What percentage of people with radiocontrast reactions have mood disorders?

Answer: unanswerable


QUES: The transition from hunting and gathering to agriculture is not necessarily a one way process. It has been argued that hunting and gathering represents an adaptive strategy, which may still be exploited, if necessary, when environmental change causes extreme food stress for agriculturalists. In fact, it is sometimes difficult to draw a clear line between agricultural and hunter-gatherer societies, especially since the widespread adoption of agriculture and resulting cultural diffusion that has occurred in the last 10,000 years.[citation needed] This anthropological view has remained unchanged since the 1960s.[clarification needed][citation needed]

It is easy to draw a clear line between what?
What is the answer?
ANS:
unanswerable