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.
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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: Reflections generally affect polarization. For radio waves, one important reflector is the ionosphere which can change the wave's polarization. Thus for signals received following reflection by the ionosphere (a skywave), a consistent polarization cannot be expected. For line-of-sight communications or ground wave propagation, horizontally or vertically polarized transmissions generally remain in about the same polarization state at the receiving location. Matching the receiving antenna's polarization to that of the transmitter can make a very substantial difference in received signal strength. Question: What reflector can change the waves polarization?

Answer: ionosphere


Question: Passage: Kerry said on September 9 in response to a reporter's question about whether Syrian President Bashar al-Assad could avert a military strike: "He could turn over every single bit of his chemical weapons to the international community in the next week. Turn it over, all of it, without delay, and allow a full and total accounting for that. But he isn't about to do it, and it can't be done, obviously." This unscripted remark initiated a process that would lead to Syria agreeing to relinquish and destroy its chemical weapons arsenal, as Russia treated Kerry's statement as a serious proposal. Russian Foreign Minister Sergey Lavrov said Russia would work "immediately" to convince Syria relinquish and destroy its large chemical weapons arsenal. Syria quickly welcomed this proposal and on September 14, the UN formally accepted Syria's application to join the convention banning chemical weapons, and separately, the U.S. and Russia agreed on a plan to eliminate Syria's chemical weapons by the middle of 2014. On September 28, the UN Security Council passed a resolution ordering the destruction of Syria's chemical weapons and condemning the August 21 Ghouta attack. Question: Who was Syria's president in 2014?

Answer:
Bashar al-Assad


