Question: A different format, CD-4 (not to be confused with compact disc), by RCA, encoded the front-rear difference information on an ultrasonic carrier, which required a special wideband cartridge to capture it on carefully calibrated pickup arm/turntable combinations. CD-4 was even less successful than the two matrixed formats. (A further problem was that no cutting heads were available that could handle the HF information. That was remedied by cutting at half the speed. Later, the special half-speed cutting heads and equalization techniques were employed to get a wider frequency response in stereo with reduced distortion and greater headroom.)
Try to answer this question if possible: How widespread was the success of CD-4 format? 
Answer: even less successful than the two matrixed formats
Question: 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.
Try to answer this question if possible: A refractor can be compared to what type of viewing?
Answer: optical lens
Question: It is in this time that the notation of music on a staff and other elements of musical notation began to take shape. This invention made possible the separation of the composition of a piece of music from its transmission; without written music, transmission was oral, and subject to change every time it was transmitted. With a musical score, a work of music could be performed without the composer's presence. The invention of the movable-type printing press in the 15th century had far-reaching consequences on the preservation and transmission of music.
Try to answer this question if possible: When was the movable-type printing press invented?
Answer: the 15th century
Question: In 2002, the Musharraf-led government took a firm stand against the jihadi organizations and groups promoting extremism, and arrested Maulana Masood Azhar, head of the Jaish-e-Mohammed, and Hafiz Muhammad Saeed, chief of the Lashkar-e-Taiba, and took dozens of activists into custody. An official ban was imposed on the groups on 12 January. Later that year, the Saudi born Zayn al-Abidn Muhammed Hasayn Abu Zubaydah was arrested by Pakistani officials during a series of joint U.S.-Pakistan raids. Zubaydah is said to have been a high-ranking al-Qaeda official with the title of operations chief and in charge of running al-Qaeda training camps. Other prominent al-Qaeda members were arrested in the following two years, namely Ramzi bin al-Shibh, who is known to have been a financial backer of al-Qaeda operations, and Khalid Sheikh Mohammed, who at the time of his capture was the third highest-ranking official in al-Qaeda and had been directly in charge of the planning for the 11 September attacks.
Try to answer this question if possible: What was the name of the Pakistani official that performed a number of raids?
Answer:
unanswerable