Last year was a record year for ice melt all over the Arctic and the ice band surrounding the North Pole is even thinner now.
去年是北极地区冰层融化创记录的一年，如今北极周围的冰带更薄了。
2
Mathematical model of wide-band oscilloscope system is established. The analysis is based on the concept of the leading pole. An approximate expression of oscilloscope system is given.