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Even before Han's expansion into Central Asia, diplomat Zhang Qian's travels from 139 to 125 BC had established Chinese contacts with many surrounding civilizations. Zhang encountered Dayuan (Fergana), Kangju (Sogdiana), and Daxia (Bactria, formerly the Greco-Bactrian Kingdom); he also gathered information on Shendu (Indus River valley of North India) and Anxi (the Parthian Empire). All of these countries eventually received Han embassies. These connections marked the beginning of the Silk Road trade network that extended to the Roman Empire, bringing Han items like silk to Rome and Roman goods such as glasswares to China.
What type of Roman item was traded on the Silk Road network?
A: glasswares

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Brasilia has also been the focus of modern-day literature. Published in 2008, The World In Grey: Dom Bosco's Prophecy, by author Ryan J. Lucero, tells an apocalypticle story based on the famous prophecy from the late 19th century by the Italian saint Don Bosco. According to Don Bosco's prophecy: "Between parallels 15 and 20, around a lake which shall be formed; A great civilization will thrive, and that will be the Promised Land." Brasilia lies between the parallels 15 S and 20 S, where an artificial lake (Paranoa Lake) was formed. Don Bosco is Brasilia's patron saint.
When was 'The World In Grey' published?
A: 2008

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Improvisation once played an important role in classical music. A remnant of this improvisatory tradition in classical music can be heard in the cadenza, a passage found mostly in concertos and solo works, designed to allow skilled performers to exhibit their virtuoso skills on the instrument. Traditionally this was improvised by the performer; however, it is often written for (or occasionally by) the performer beforehand. Improvisation is also an important aspect in authentic performances of operas of Baroque era and of bel canto (especially operas of Vincenzo Bellini), and is best exemplified by the da capo aria, a form by which famous singers typically perform variations of the thematic matter of the aria in the recapitulation section ('B section' / the 'da capo' part). An example is Beverly Sills' complex, albeit pre-written, variation of Da tempeste il legno infranto from Handel's Giulio Cesare.
Where can a remnant of improvisation tradition be found?
A: cadenza

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Providing sufficient base drive current is a key problem in the use of bipolar transistors as switches. The transistor provides current gain, allowing a relatively large current in the collector to be switched by a much smaller current into the base terminal. The ratio of these currents varies depending on the type of transistor, and even for a particular type, varies depending on the collector current. In the example light-switch circuit shown, the resistor is chosen to provide enough base current to ensure the transistor will be saturated.
What is a major problem with using bipolar transistors as switches?
A:
Providing sufficient base drive current