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 needs consistency?, Context: The simplest valve gears give events of fixed length during the engine cycle and often make the engine rotate in only one direction. Most however have a reversing mechanism which additionally can provide means for saving steam as speed and momentum are gained by gradually "shortening the cutoff" or rather, shortening the admission event; this in turn proportionately lengthens the expansion period. However, as one and the same valve usually controls both steam flows, a short cutoff at admission adversely affects the exhaust and compression periods which should ideally always be kept fairly constant; if the exhaust event is too brief, the totality of the exhaust steam cannot evacuate the cylinder, choking it and giving excessive compression ("kick back").[citation needed]
[EX A]: exhaust and compression periods

[EX Q]: What creature could be found besides two sea lions?, Context: "Azure, three ships with three masts, rigged and under full sail, the sails, pennants and ensigns Argent, each charged with a cross Gules; on a chief of the second a pale quarterly Azure and Gules, on the 1st and 4th a fleur-de-lis or, on the 2nd and 3rd a leopard or, between two roses Gules seeded Or barbed Vert." The shield had as a crest: "A sphere without a frame, bounded with the Zodiac in bend Or, between two pennants flottant Argent, each charged with a cross Gules, over the sphere the words DEUS INDICAT" (Latin: God Indicates). The supporters were two sea lions (lions with fishes' tails) and the motto was DEO DUCENTE NIL NOCET (Latin: Where God Leads, Nothing Hurts).
[EX A]: leopard

[EX Q]: What must users pay for to use?, Context: PlayStation Plus (commonly abbreviated PS+ and occasionally referred to as PSN Plus) is a premium PlayStation Network subscription service that was officially unveiled at E3 2010 by Jack Tretton, President and CEO of SCEA. Rumors of such service had been in speculation since Kaz Hirai's announcement at TGS 2009 of a possible paid service for PSN but with the current PSN service still available. Launched alongside PS3 firmware 3.40 and PSP firmware 6.30 on June 29, 2010, the paid-for subscription service provides users with enhanced services on the PlayStation Network, on top of the current PSN service which is still available with all of its features. These enhancements include the ability to have demos, game and system software updates download automatically to PlayStation 3. Subscribers also get early or exclusive access to some betas, game demos, premium downloadable content and other PlayStation Store items. North American users also get a free subscription to Qore. Users may choose to purchase either a one-year or a three-month subscription to PlayStation Plus.
[EX A]:
PlayStation Network subscription service

