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

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]
exhaust and compression periods

What did NBC delay for the west coast primetime?, Context: CBC's sports coverage has also attained high viewership in border markets, including its coverage of the NHL's Stanley Cup Playoffs, which was generally considered to be more complete and consistent than coverage by other networks such as NBC. Its coverage of the Olympic Games also found a significant audience in border regions, primarily due to the fact that CBC aired more events live than NBC's coverage, which had been criticized in recent years for tape delaying events to air in primetime, even if the event is being held in a market in the Pacific Time Zone during primetime hours on the East (where it would still be delayed for West coast primetime).
Olympic Games

How are delegates chosen to go to the US?, Context: Since 1898, Puerto Rico has had limited representation in the Congress in the form of a Resident Commissioner, a nonvoting delegate. The 110th Congress returned the Commissioner's power to vote in the Committee of the Whole, but not on matters where the vote would represent a decisive participation. Puerto Rico has elections on the United States presidential primary or caucus of the Democratic Party and the Republican Party to select delegates to the respective parties' national conventions although presidential electors are not granted on the Electoral College. As American citizens, Puerto Ricans can vote in U.S. presidential elections, provided they reside in one of the 50 states or the District of Columbia and not in Puerto Rico itself.

elections