In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

[EX Q]: What do you need in addition to the LaserDisc in order to experience surround sound?, Context: Only one 5.1 surround sound option exists on a given LaserDisc (either Dolby Digital or DTS), so if surround sound is desired, the disc must be matched to the capabilities of the playback equipment (LD Player and Receiver/Decoder) by the purchaser. A fully capable LaserDisc playback system includes a newer LaserDisc player that is capable of playing digital tracks, has a digital optical output for digital PCM and DTS audio, is aware of AC-3 audio tracks, and has an AC-3 coaxial output; an external or internal AC-3 RF demodulator and AC-3 decoder; and a DTS decoder. Many 1990s A/V receivers combine the AC-3 decoder and DTS decoder logic, but an integrated AC-3 demodulator is rare both in LaserDisc players and in later A/V receivers.
[EX A]: playback equipment

[EX Q]: How known was the phrase used?, Context: The only words of Jesus on the cross in the Mark and Matthew accounts, this is a quotation of Psalm 22. Since other verses of the same Psalm are cited in the crucifixion accounts, it is often considered a literary and theological creation. Geza Vermes, however, points out that the verse is cited in Aramaic rather than the Hebrew in which it usually would have been recited, and suggests that by the time of Jesus, this phrase had become a proverbial saying in common usage. Compared to the accounts in the other Gospels, which he describes as 'theologically correct and reassuring', he considers this phrase 'unexpected, disquieting and in consequence more probable'. He describes it as bearing 'all the appearances of a genuine cry'. Raymond Brown likewise comments that he finds 'no persuasive argument against attributing to the Jesus of Mark/Matt the literal sentiment of feeling forsaken expressed in the Psalm quote'.
[EX A]: in common usage

[EX Q]: The current strength depends indirectly on the amount of what?, Context: Ion gauges are used in ultrahigh vacuum. They come in two types: hot cathode and cold cathode. In the hot cathode version an electrically heated filament produces an electron beam. The electrons travel through the gauge and ionize gas molecules around them. The resulting ions are collected at a negative electrode. The current depends on the number of ions, which depends on the pressure in the gauge. Hot cathode gauges are accurate from 10−3 torr to 10−10 torr. The principle behind cold cathode version is the same, except that electrons are produced in a discharge created by a high voltage electrical discharge. Cold cathode gauges are accurate from 10−2 torr to 10−9 torr. Ionization gauge calibration is very sensitive to construction geometry, chemical composition of gases being measured, corrosion and surface deposits. Their calibration can be invalidated by activation at atmospheric pressure or low vacuum. The composition of gases at high vacuums will usually be unpredictable, so a mass spectrometer must be used in conjunction with the ionization gauge for accurate measurement.
[EX A]:
gas molecules

