instruction:
In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
question:
Why do birds possess gizzards?, Context: Like the reptiles, birds are primarily uricotelic, that is, their kidneys extract nitrogenous waste from their bloodstream and excrete it as uric acid instead of urea or ammonia through the ureters into the intestine. Birds do not have a urinary bladder or external urethral opening and (with exception of the ostrich) uric acid is excreted along with feces as a semisolid waste. However, birds such as hummingbirds can be facultatively ammonotelic, excreting most of the nitrogenous wastes as ammonia. They also excrete creatine, rather than creatinine like mammals. This material, as well as the output of the intestines, emerges from the bird's cloaca. The cloaca is a multi-purpose opening: waste is expelled through it, most birds mate by joining cloaca, and females lay eggs from it. In addition, many species of birds regurgitate pellets. Males within Palaeognathae (with the exception of the kiwis), the Anseriformes (with the exception of screamers), and in rudimentary forms in Galliformes (but fully developed in Cracidae) possess a penis, which is never present in Neoaves. The length is thought to be related to sperm competition. When not copulating, it is hidden within the proctodeum compartment within the cloaca, just inside the vent. The digestive system of birds is unique, with a crop for storage and a gizzard that contains swallowed stones for grinding food to compensate for the lack of teeth. Most birds are highly adapted for rapid digestion to aid with flight. Some migratory birds have adapted to use protein from many parts of their bodies, including protein from the intestines, as additional energy during migration.
answer:
contains swallowed stones for grinding food to compensate for the lack of teeth


question:
What was the harshest form of oppression faced by Jewish populations?, Context: Throughout history, many rulers, empires and nations have oppressed their Jewish populations or sought to eliminate them entirely. Methods employed ranged from expulsion to outright genocide; within nations, often the threat of these extreme methods was sufficient to silence dissent. The history of antisemitism includes the First Crusade which resulted in the massacre of Jews; the Spanish Inquisition (led by Tomás de Torquemada) and the Portuguese Inquisition, with their persecution and autos-da-fé against the New Christians and Marrano Jews; the Bohdan Chmielnicki Cossack massacres in Ukraine; the Pogroms backed by the Russian Tsars; as well as expulsions from Spain, Portugal, England, France, Germany, and other countries in which the Jews had settled. According to a 2008 study published in the American Journal of Human Genetics, 19.8% of the modern Iberian population has Sephardic Jewish ancestry, indicating that the number of conversos may have been much higher than originally thought.
answer:
genocide


question:
Who was in Taiwan for almost two decades?, Context: To extend and consolidate the dynasty's control in Central Asia, the Kangxi Emperor personally led a series of military campaigns against the Dzungars in Outer Mongolia. The Kangxi Emperor was able to successfully expel Galdan's invading forces from these regions, which were then incorporated into the empire. Galdan was eventually killed in the Dzungar–Qing War. In 1683, Qing forces received the surrender of Taiwan from Zheng Keshuang, grandson of Koxinga, who had conquered Taiwan from the Dutch colonists as a base against the Qing. Zheng Keshuang was awarded the title "Duke Haicheng" (海澄公) and was inducted into the Han Chinese Plain Red Banner of the Eight Banners when he moved to Beijing. Several Ming princes had accompanied Koxinga to Taiwan in 1661-1662, including the Prince of Ningjing Zhu Shugui and Prince Zhu Honghuan (朱弘桓), son of Zhu Yihai, where they lived in the Kingdom of Tungning. The Qing sent the 17 Ming princes still living on Taiwan in 1683 back to mainland China where they spent the rest of their lives in exile since their lives were spared from execution. Winning Taiwan freed Kangxi's forces for series of battles over Albazin, the far eastern outpost of the Tsardom of Russia. Zheng's former soldiers on Taiwan like the rattan shield troops were also inducted into the Eight Banners and used by the Qing against Russian Cossacks at Albazin. The 1689 Treaty of Nerchinsk was China's first formal treaty with a European power and kept the border peaceful for the better part of two centuries. After Galdan's death, his followers, as adherents to Tibetan Buddhism, attempted to control the choice of the next Dalai Lama. Kangxi dispatched two armies to Lhasa, the capital of Tibet, and installed a Dalai Lama sympathetic to the Qing.
answer:

Ming princes