Problem: The state of California was admitted to the United States in 1850. That same year San Diego was designated the seat of the newly established San Diego County and was incorporated as a city. Joshua H. Bean, the last alcalde of San Diego, was elected the first mayor. Two years later the city was bankrupt; the California legislature revoked the city's charter and placed it under control of a board of trustees, where it remained until 1889. A city charter was re-established in 1889 and today's city charter was adopted in 1931.
When was San Francisco's current charter adopted?
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Answer: unanswerable

Problem: The actual resistance of the filament is temperature dependent. The cold resistance of tungsten-filament lamps is about 1/15 the hot-filament resistance when the lamp is operating. For example, a 100-watt, 120-volt lamp has a resistance of 144 ohms when lit, but the cold resistance is much lower (about 9.5 ohms). Since incandescent lamps are resistive loads, simple phase-control TRIAC dimmers can be used to control brightness. Electrical contacts may carry a "T" rating symbol indicating that they are designed to control circuits with the high inrush current characteristic of tungsten lamps. For a 100-watt, 120-volt general-service lamp, the current stabilizes in about 0.10 seconds, and the lamp reaches 90% of its full brightness after about 0.13 seconds.
What determines the resistance of a filament?
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Answer: temperature

Problem: The atolls have shown resilience to gradual sea-level rise, with atolls and reef islands being able to grow under current climate conditions by generating sufficient sand and coral debris that accumulates and gets dumped on the islands during cyclones. Gradual sea-level rise also allows for coral polyp activity to increase the reefs. However, if the increase in sea level occurs at faster rate as compared to coral growth, or if polyp activity is damaged by ocean acidification, then the resilience of the atolls and reef islands is less certain. The 2011 report of Pacific Climate Change Science Program of Australia concludes, in relation to Tuvalu, states the conclusions that over the course of the 21st century:
What condition besides sea level rise can damage coral reefs?
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Answer:
ocean acidification