Input: Hunter-gatherer
Mutual exchange and sharing of resources (i.e., meat gained from hunting) are important in the economic systems of hunter-gatherer societies. Therefore, these societies can be described as based on a "gift economy."

What other characteristic of group behavior is needed in a hunter-gatherer society?
Output: sharing

Input: Planck constant
Classical statistical mechanics requires the existence of h (but does not define its value). Eventually, following upon Planck's discovery, it was recognized that physical action cannot take on an arbitrary value. Instead, it must be some multiple of a very small quantity, the "quantum of action", now called the Planck constant. Classical physics cannot explain this fact. In many cases, such as for monochromatic light or for atoms, this quantum of action also implies that only certain energy levels are allowed, and values in between are forbidden.

What is required to exist in classical statistics mechanics?
Output: h

Input: Pacific War
Japan sponsored several puppet governments, one of which was headed by Wang Jingwei. However, its policies of brutality toward the Chinese population, of not yielding any real power to these regimes, and of supporting several rival governments failed to make any of them a viable alternative to the Nationalist government led by Chiang Kai-shek. Conflicts between Chinese communist and nationalist forces vying for territory control behind enemy lines culminated in a major armed clash in January 1941, effectively ending their co-operation.

What was Wang Jingwei's government considered?
Output: puppet

Input: Roman Republic
The exact causes and motivations for Rome's military conflicts and expansions during the republic are subject to wide debate. While they can be seen as motivated by outright aggression and imperialism, historians typically take a much more nuanced view. They argue that Rome's expansion was driven by short-term defensive and inter-state factors (that is, relations with city-states and kingdoms outside Rome's hegemony), and the new contingencies that these decisions created. In its early history, as Rome successfully defended itself against foreign threats in central and then northern Italy, neighboring city-states sought the protection a Roman alliance would bring. As such, early republican Rome was not an "empire" or "state" in the modern sense, but an alliance of independent city-states (similar to the Greek hegemonies of the same period) with varying degrees of genuine independence (which itself changed over time) engaged in an alliance of mutual self-protection, but led by Rome. With some important exceptions, successful wars in early republican Rome generally led not to annexation or military occupation, but to the restoration of the way things were. But the defeated city would be weakened (sometimes with outright land concessions) and thus less able to resist Romanizing influences, such as Roman settlers seeking land or trade with the growing Roman confederacy. It was also less able to defend itself against its non-Roman enemies, which made attack by these enemies more likely. It was, therefore, more likely to seek an alliance of protection with Rome.

What factor is considered by some to be the main driving force behind the expansion of Rome?
Output:
inter-state factors