In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

Q: Tibet's incursions into Sichuan can be classified as what during the Tang Dynasty?, Context: Sichuan came under the firm control of a Chinese central government during the Sui dynasty, but it was during the subsequent Tang dynasty where Sichuan regained its previous political and cultural prominence for which it was known during the Han. Chengdu became nationally known as a supplier of armies and the home of Du Fu, who is sometimes called China's greatest poet. During the An Lushan Rebellion (755-763), Emperor Xuanzong of Tang fled from Chang'an to Sichuan. The region was torn by constant warfare and economic distress as it was besieged by the Tibetan Empire.

A: constant
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Q: How was Nintendo Entertainment System software distributed?, Context: To differentiate Nintendo's new home platform from the early 1980s' common perception of a troubled and shallow video game market, the company freshened its product nomenclature and positioning, and it established a strict product approval and licensing policy. The overall system was referred to as an "Entertainment System" instead of a "video game system", which was centered upon a machine called a "Control Deck" instead of a "console", and which featured software cartridges called "Game Paks" instead of "video games". The 10NES lockout chip system acted as a lock-and-key coupling of each Game Pak and Control Deck, deterring the copying or production of NES games which had not first achieved Nintendo's licensed approval. The packaging of the launch lineup of NES games bore pictures of a very close representation of the actual onscreen graphics of the game, which were of sufficiently recognizable quality on their own. Symbols on the launch games' packaging clearly indicated the genre of the game, in order to reduce consumer confusion. A 'seal of quality' was printed on all appropriately licensed game and accessory packaging. The initial seal stated, "This seal is your assurance that Nintendo has approved and guaranteed the quality of this product". This text was later changed to "Official Nintendo Seal of Quality".

A: software cartridges
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Q: Before a pathogen can trigger an innate immune response, it must overcome what type of defense?, Context: The immune system protects organisms from infection with layered defenses of increasing specificity. In simple terms, physical barriers prevent pathogens such as bacteria and viruses from entering the organism. If a pathogen breaches these barriers, the innate immune system provides an immediate, but non-specific response. Innate immune systems are found in all plants and animals. If pathogens successfully evade the innate response, vertebrates possess a second layer of protection, the adaptive immune system, which is activated by the innate response. Here, the immune system adapts its response during an infection to improve its recognition of the pathogen. This improved response is then retained after the pathogen has been eliminated, in the form of an immunological memory, and allows the adaptive immune system to mount faster and stronger attacks each time this pathogen is encountered.

A:
physical barriers
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