Here is a question about this article: Immunology is strongly experimental in everyday practice but is also characterized by an ongoing theoretical attitude. Many theories have been suggested in immunology from the end of the nineteenth century up to the present time. The end of the 19th century and the beginning of the 20th century saw a battle between "cellular" and "humoral" theories of immunity. According to the cellular theory of immunity, represented in particular by Elie Metchnikoff, it was cells more precisely, phagocytes that were responsible for immune responses. In contrast, the humoral theory of immunity, held by Robert Koch and Emil von Behring, among others, stated that the active immune agents were soluble components (molecules) found in the organism's "humors" rather than its cells.
What is the answer to this question: What are two opposing theories of early 20th century immunology?
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So... "cellular" and "humoral"

Here is a question about this article: The games are in the form of .ipg files, which are actually .zip archives in disguise[citation needed]. When unzipped, they reveal executable files along with common audio and image files, leading to the possibility of third party games. Apple has not publicly released a software development kit (SDK) for iPod-specific development. Apps produced with the iPhone SDK are compatible only with the iOS on the iPod Touch and iPhone, which cannot run clickwheel-based games.
What is the answer to this question: What is the only operating system on which iPhone SDK-made games can be played?
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So... iOS

Here is a question about this article: 35th Street runs from FDR Drive to Eleventh Avenue. Notable locations include East River Ferry, LaptopMD headquarters, Mercy College Manhattan Campus, and Jacob K. Javits Convention Center.
What is the answer to this question: Which street runs from FDR Drive to Eleventh Avenue?
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So...
35th Street