Starting in 2007, daylight time begins in the United States on the second Sunday in March and ends on the first Sunday in November. On the second Sunday in March, clocks are set ahead one hour at 2:00 a.m. local standard time, which becomes 3:00 a.m. local daylight time. On the first Sunday in November, clocks are set back one hour at 2:00 a.m. local daylight time, which becomes 1:00 a.m. local standard time. These dates were established by Congress in the Energy Policy Act of 2005, Pub. L. no. 109-58, 119 Stat 594 (2005).
Not all places in the U.S. observe daylight time. In particular, Hawaii and most of Arizona do not use it. Indiana adopted its use beginning in 2006
The question is why "... clocks are set ahead one hour at 2:00 a.m..."?
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Không cười thì lỗ ráng chịu nghen ^_*
làm gì vậy??? giới thiệu cho LH999 đi 
kiểu này LH999 thế nào cũng bị hớ 
chưa kể muốn nghỉ khi nào thì cứ nghỉ, chỉ cần call in sick