Question: The Chronicle reports that Askold and Dir continued to Constantinople with a navy to attack the city in 86366, catching the Byzantines by surprise and ravaging the surrounding area, though other accounts date the attack in 860. Patriarch Photius vividly describes the "universal" devastation of the suburbs and nearby islands, and another account further details the destruction and slaughter of the invasion. The Rus' turned back before attacking the city itself, due either to a storm dispersing their boats, the return of the Emperor, or in a later account, due to a miracle after a ceremonial appeal by the Patriarch and the Emperor to the Virgin. The attack was the first encounter between the Rus' and Byzantines and led the Patriarch to send missionaries north to engage and attempt to convert the Rus' and the Slavs.
Is there an answer to this question: What did the attack between Rus and Byzantines lead to?

Answer: Patriarch to send missionaries north to engage

Question: Active solar techniques use photovoltaics, concentrated solar power, solar thermal collectors, pumps, and fans to convert sunlight into useful outputs. Passive solar techniques include selecting materials with favorable thermal properties, designing spaces that naturally circulate air, and referencing the position of a building to the Sun. Active solar technologies increase the supply of energy and are considered supply side technologies, while passive solar technologies reduce the need for alternate resources and are generally considered demand side technologies.
Is there an answer to this question: What does a passive solar technique do?

Answer: reduce the need for alternate resources

Question: Contemporary a cappella includes many vocal groups and bands who add vocal percussion or beatboxing to create a pop/rock/gospel sound, in some cases very similar to bands with instruments. Examples of such professional groups include Straight No Chaser, Pentatonix, The House Jacks, Rockapella, Mosaic, and M-pact. There also remains a strong a cappella presence within Christian music, as some denominations purposefully do not use instruments during worship. Examples of such groups are Take 6, Glad and Acappella. Arrangements of popular music for small a cappella ensembles typically include one voice singing the lead melody, one singing a rhythmic bass line, and the remaining voices contributing chordal or polyphonic accompaniment.
Is there an answer to this question: What has maintained a strong presence in all types of worship?

Answer: unanswerable

Question: The Han dynasty was an age of economic prosperity and saw a significant growth of the money economy first established during the Zhou dynasty (c. 1050256 BC). The coinage issued by the central government mint in 119 BC remained the standard coinage of China until the Tang dynasty (618907 AD). The period saw a number of limited institutional innovations. To pay for its military campaigns and the settlement of newly conquered frontier territories, the government nationalized the private salt and iron industries in 117 BC, but these government monopolies were repealed during the Eastern Han period. Science and technology during the Han period saw significant advances, including papermaking, the nautical steering rudder, the use of negative numbers in mathematics, the raised-relief map, the hydraulic-powered armillary sphere for astronomy, and a seismometer employing an inverted pendulum.
Is there an answer to this question: A seismometer during the Han dynasty used what type of pendulum?

Answer:
inverted