instruction:
This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.
question:
Passage: An electromagnetic wave refractor in some aperture antennas is a component which due to its shape and position functions to selectively delay or advance portions of the electromagnetic wavefront passing through it. The refractor alters the spatial characteristics of the wave on one side relative to the other side. It can, for instance, bring the wave to a focus or alter the wave front in other ways, generally in order to maximize the directivity of the antenna system. This is the radio equivalent of an optical lens. Question: What is used to allow one to control the function of wave fronts moving through an antenna?
answer:
selectively delay


question:
Passage: By August 1805, Napoleon had realized that the strategic situation had changed fundamentally. Facing a potential invasion from his continental enemies, he decided to strike first and turned his army's sights from the English Channel to the Rhine. His basic objective was to destroy the isolated Austrian armies in Southern Germany before their Russian allies could arrive. On 25 September, after great secrecy and feverish marching, 200,000 French troops began to cross the Rhine on a front of 260 km (160 mi). Austrian commander Karl Mack had gathered the greater part of the Austrian army at the fortress of Ulm in Swabia. Napoleon swung his forces to the southeast and the Grande Armée performed an elaborate wheeling movement that outflanked the Austrian positions. The Ulm Maneuver completely surprised General Mack, who belatedly understood that his army had been cut off. After some minor engagements that culminated in the Battle of Ulm, Mack finally surrendered after realizing that there was no way to break out of the French encirclement. For just 2000 French casualties, Napoleon had managed to capture a total of 60,000 Austrian soldiers through his army's rapid marching. The Ulm Campaign is generally regarded as a strategic masterpiece and was influential in the development of the Schlieffen Plan in the late 19th century. For the French, this spectacular victory on land was soured by the decisive victory that the Royal Navy attained at the Battle of Trafalgar on 21 October. After Trafalgar, Britain had total domination of the seas for the duration of the Napoleonic Wars. Question: By August 1805, Napoleon changed the primary target of his army's efforts from the English Channel to what area?
answer:
the Rhine


question:
Passage: During the 1800s Christian missionaries from Great Britain and the United States followed traders to the Hawaiian islands. Long-termly, the Anglo-Saxon presence negatively impacted the level of regard Hawaiian royal women held for their own indigenous looks. For centuries prior the arrival of Christians, first nation Hawaiian aesthetics, such as dark skin and ample bodies, had been considered signs of nobility. No matter how much they adapted their mannerisms to Western standard, some of the Anglo-Saxon missionaries were relentless in referring to the indigenous women as "Hawaiian squaws." By the last half of the 19th century, some Hawaiian women began marrying European men who found them exotic. The men, however, selected Hawaiian women who were thinner and paler in complexion. Question: When would white men marry the paler and thinner Hawaiian ladies?
answer:

By the last half of the 19th century