Problem: Railway electrification system:

An early advantage of AC is that the power-wasting resistors used in DC locomotives for speed control were not needed in an AC locomotive: multiple taps on the transformer can supply a range of voltages. Separate low-voltage transformer windings supply lighting and the motors driving auxiliary machinery. More recently, the development of very high power semiconductors has caused the classic "universal" AC/DC motor to be largely replaced with the three-phase induction motor fed by a variable frequency drive, a special inverter that varies both frequency and voltage to control motor speed. These drives can run equally well on DC or AC of any frequency, and many modern electric locomotives are designed to handle different supply voltages and frequencies to simplify cross-border operation.

What taps can provide lighting supply?
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A: low-voltage transformer windings


Problem: Muammar Gaddafi:

Gaddafi's earliest education was of a religious nature, imparted by a local Islamic teacher. Subsequently moving to nearby Sirte to attend elementary school, he progressed through six grades in four years. Education in Libya was not free, but his father thought it would greatly benefit his son despite the financial strain. During the week Gaddafi slept in a mosque, and at weekends walked 20 miles to visit his parents. Bullied for being a Bedouin, he was proud of his identity and encouraged pride in other Bedouin children. From Sirte, he and his family moved to the market town of Sabha in Fezzan, south-central Libya, where his father worked as a caretaker for a tribal leader while Muammar attended secondary school, something neither parent had done. Gaddafi was popular at school; some friends made there received significant jobs in his later administration, most notably his best friend Abdul Salam Jalloud.

Why was Gaddafi made fun of in elementary school?
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A: Bullied for being a Bedouin, he was proud of his identity and encouraged pride in other Bedouin children.


Problem: Sexual orientation:

Most definitions of sexual orientation include a psychological component, such as the direction of an individual's erotic desires, or a behavioral component, which focuses on the sex of the individual's sexual partner/s. Some people prefer simply to follow an individual's self-definition or identity. Scientific and professional understanding is that "the core attractions that form the basis for adult sexual orientation typically emerge between middle childhood and early adolescence". Sexual orientation differs from sexual identity in that it encompasses relationships with others, while sexual identity is a concept of self.

What do other people use to determine a persons sexual idenity?
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A: an individual's self-definition


Problem: Myocardial infarction:

Cardiac rehabilitation benefits many who have experienced myocardial infarction, even if there has been substantial heart damage and resultant left ventricular failure; ideally other medical conditions that could interfere with participation should be managed optimally. It should start soon after discharge from hospital. The program may include lifestyle advice, exercise, social support, as well as recommendations about driving, flying, sport participation, stress management, and sexual intercourse.

When are other medical conditions address?
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A:
unanswerable