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.

Q: Passage: Returning to the basic concept of current flows in a conductor, consider what happens if a half-wave dipole is not connected to a feed point, but instead shorted out. Electrically this forms a single 1⁄2-wavelength element. But the overall current pattern is the same; the current will be zero at the two ends, and reach a maximum in the center. Thus signals near the design frequency will continue to create a standing wave pattern. Any varying electrical current, like the standing wave in the element, will radiate a signal. In this case, aside from resistive losses in the element, the rebroadcast signal will be significantly similar to the original signal in both magnitude and shape. If this element is placed so its signal reaches the main dipole in-phase, it will reinforce the original signal, and increase the current in the dipole. Elements used in this way are known as passive elements. Question: What is a half wave dipole need to be coupled with in most instances?

A: feed point
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Q: Passage: From the caliphate's north-western African bases, a series of raids on coastal areas of the Visigothic Kingdom paved the way to the permanent occupation of most of Iberia by the Umayyads (starting in 711), and on into south-eastern Gaul (last stronghold at Narbonne in 759). Hisham's reign witnessed the end of expansion in the west, following the defeat of the Arab army by the Franks at the Battle of Tours in 732. In 739 a major Berber Revolt broke out in North Africa, which was subdued only with difficulty, but it was followed by the collapse of Umayyad authority in al-Andalus. In India the Arab armies were defeated by the south Indian Chalukya dynasty and by the north Indian Pratiharas Dynasty in the 8th century and the Arabs were driven out of India. In the Caucasus, the confrontation with the Khazars peaked under Hisham: the Arabs established Derbent as a major military base and launched several invasions of the northern Caucasus, but failed to subdue the nomadic Khazars. The conflict was arduous and bloody, and the Arab army even suffered a major defeat at the Battle of Marj Ardabil in 730. Marwan ibn Muhammad, the future Marwan II, finally ended the war in 737 with a massive invasion that is reported to have reached as far as the Volga, but the Khazars remained unsubdued. Question: Who defeated the Arabs at the Battle of Tours?

A: Franks
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Q: Passage: Decoding, on the other hand, is carefully defined in the standard. Most decoders are "bitstream compliant", which means that the decompressed output that they produce from a given MP3 file will be the same, within a specified degree of rounding tolerance, as the output specified mathematically in the ISO/IEC high standard document (ISO/IEC 11172-3). Therefore, comparison of decoders is usually based on how computationally efficient they are (i.e., how much memory or CPU time they use in the decoding process). Question: What is carefully defined in the standard?

A:
Decoding
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