Question: Central station electricity can often be generated with higher efficiency than a mobile engine/generator. While the efficiency of power plant generation and diesel locomotive generation are roughly the same in the nominal regime, diesel motors decrease in efficiency in non-nominal regimes at low power while if an electric power plant needs to generate less power it will shut down its least efficient generators, thereby increasing efficiency. The electric train can save energy (as compared to diesel) by regenerative braking and by not needing to consume energy by idling as diesel locomotives do when stopped or coasting. However, electric rolling stock may run cooling blowers when stopped or coasting, thus consuming energy.
Is there an answer to this question: What can often be generated with a lower efficiency?

Answer: unanswerable

Question: Though Han wooden structures decayed, some Han-dynasty ruins made of brick, stone, and rammed earth remain intact. This includes stone pillar-gates, brick tomb chambers, rammed-earth city walls, rammed-earth and brick beacon towers, rammed-earth sections of the Great Wall, rammed-earth platforms where elevated halls once stood, and two rammed-earth castles in Gansu. The ruins of rammed-earth walls that once surrounded the capitals Chang'an and Luoyang still stand, along with their drainage systems of brick arches, ditches, and ceramic water pipes. Monumental stone pillar-gates, twenty-nine of which survive from the Han period, formed entrances of walled enclosures at shrine and tomb sites. These pillars feature artistic imitations of wooden and ceramic building components such as roof tiles, eaves, and balustrades.
Is there an answer to this question: What building material were tomb chambers constructed with?

Answer: brick

Question: With characteristic energy he set to work to re-establish the somewhat shattered fortunes of the orthodox party and to purge the theological atmosphere of uncertainty. To clear up the misunderstandings that had arisen in the course of the previous years, an attempt was made to determine still further the significance of the Nicene formularies. In the meanwhile, Julian, who seems to have become suddenly jealous of the influence that Athanasius was exercising at Alexandria, addressed an order to Ecdicius, the Prefect of Egypt, peremptorily commanding the expulsion of the restored primate, on the ground that he had never been included in the imperial act of clemency. The edict was communicated to the bishop by Pythicodorus Trico, who, though described in the "Chronicon Athanasianum" (XXXV) as a "philosopher", seems to have behaved with brutal insolence. On 23 October the people gathered about the proscribed bishop to protest against the emperor's decree; but Athanasius urged them to submit, consoling them with the promise that his absence would be of short duration.
Is there an answer to this question: What did Athanasius not tell the people?

Answer: unanswerable

Question: There are very few existing mosaics from the Komnenian period but this paucity must be due to accidents of survival and gives a misleading impression. The only surviving 12th-century mosaic work in Constantinople is a panel in Hagia Sophia depicting Emperor John II and Empress Eirene with the Theotokos (112234). The empress with her long braided hair and rosy cheeks is especially capturing. It must be a lifelike portrayal because Eirene was really a redhead as her original Hungarian name, Piroska shows. The adjacent portrait of Emperor Alexios I Komnenos on a pier (from 1122) is similarly personal. The imperial mausoleum of the Komnenos dynasty, the Pantokrator Monastery was certainly decorated with great mosaics but these were later destroyed. The lack of Komnenian mosaics outside the capital is even more apparent. There is only a "Communion of the Apostles" in the apse of the cathedral of Serres.
Is there an answer to this question: Where is the only existing 12th century mosaic in Constantinople?

Answer:
Hagia Sophia