Problem: As the years went by, the three feudal lords and their extensive territories became increasingly autonomous. Finally, in 1673, Shang Kexi petitioned Kangxi for permission to retire to his hometown in Liaodong province and nominated his son as his successor. The young emperor granted his retirement, but denied the heredity of his fief. In reaction, the two other generals decided to petition for their own retirements to test Kangxi's resolve, thinking that he would not risk offending them. The move backfired as the young emperor called their bluff by accepting their requests and ordering that all three fiefdoms to be reverted to the crown.
When did Kexi retire?
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Answer: 1673

Problem: There are many non-incandescent light sources, such as the fluorescent lamp, high-intensity discharge lamps and LED lamps, which have higher luminous efficiency, and some have been designed to be retrofitted in fixtures for incandescent lights. These devices produce light by luminescence. These lamps produce discrete spectral lines and do not have the broad "tail" of invisible infrared emissions. By careful selection of which electron energy level transitions are used, and fluorescent coatings which modify the spectral distribution, the spectrum emitted can be tuned to mimic the appearance of incandescent sources, or other different color temperatures of white light. Due to the discrete spectral lines rather than a continuous spectrum, the light is not ideal for applications such as photography and cinematography.
Why are luminescent light sources ideal for photography?
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Answer: unanswerable

Problem: Conventional ("tailhook") aircraft rely upon a landing signal officer (LSO, radio call sign paddles) to monitor the aircraft's approach, visually gauge glideslope, attitude, and airspeed, and transmit that data to the pilot. Before the angled deck emerged in the 1950s, LSOs used colored paddles to signal corrections to the pilot (hence the nickname). From the late 1950s onward, visual landing aids such as Optical Landing System have provided information on proper glide slope, but LSOs still transmit voice calls to approaching pilots by radio.
What are LSO's still being used to do?
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Answer:
transmit voice calls to approaching pilots by radio