某设备在不同的使用年限(一年到七年)下，年资产消耗成本和年运行成本如下表（单位；万元）则该设备的经济寿命为（ ）年 <table style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; BORDER-COLLAPSE: collapse; MARGIN-LEFT: 6.75pt; BORDER-TOP: medium none; MARGIN-RIGHT: 6.75pt; BORDER-RIGHT: medium none" border="1" cellspacing="0" cellpadding="0" align="left" _dj="MsoNormalTable"><tbody><tr style="HEIGHT: 13.35pt"><td style="BORDER-BOTTOM: black 1pt solid; BORDER-LEFT: black 1pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 82.35pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.35pt; BORDER-TOP: black 1pt solid; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm" valign="top" width="110">使用年限</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 45pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.35pt; BORDER-TOP: 1pt solid; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="60">1</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 21.6pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.35pt; BORDER-TOP: 1pt solid; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="29">2</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 42pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.35pt; BORDER-TOP: 1pt solid; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="56">3</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 42.05pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.35pt; BORDER-TOP: 1pt solid; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="56">4</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 42pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.35pt; BORDER-TOP: 1pt solid; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="56">5</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 42pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.35pt; BORDER-TOP: 1pt solid; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="56">6</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 42pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.35pt; BORDER-TOP: 1pt solid; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="56">7</td></tr><tr style="HEIGHT: 11.5pt"><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: 1pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 82.35pt; PADDING-RIGHT: 5.4pt; HEIGHT: 11.5pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="110">年资产消耗成本</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 45pt; PADDING-RIGHT: 5.4pt; HEIGHT: 11.5pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="60">90</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 21.6pt; PADDING-RIGHT: 5.4pt; HEIGHT: 11.5pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="29">50</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 42pt; PADDING-RIGHT: 5.4pt; HEIGHT: 11.5pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="56">35</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 42.05pt; PADDING-RIGHT: 5.4pt; HEIGHT: 11.5pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="56">23</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 42pt; PADDING-RIGHT: 5.4pt; HEIGHT: 11.5pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="56">20</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 42pt; PADDING-RIGHT: 5.4pt; HEIGHT: 11.5pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="56">18</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 42pt; PADDING-RIGHT: 5.4pt; HEIGHT: 11.5pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="56">15</td></tr><tr style="HEIGHT: 13.9pt"><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: 1pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 82.35pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.9pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="110">年运行成本</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 45pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.9pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="60">20</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 21.6pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.9pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="29">25</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 42pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.9pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="56">30</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 42.05pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.9pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="56">35</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 42pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.9pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="56">40</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 42pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.9pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="56">45</td><td style="BORDER-BOTTOM: 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 42pt; PADDING-RIGHT: 5.4pt; HEIGHT: 13.9pt; BORDER-TOP: medium none; BORDER-RIGHT: 1pt solid; PADDING-TOP: 0cm" valign="top" width="56">60</td></tr></tbody></table>