argin: 0cm 0cm 0pt 39pt; text-indent: -21pt"><span style="font-size: medium"><span style="color: black">1.<span style="font: 7pt 'Times New Roman'">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span><span style="color: black">两个端点所在的格子在网格的边界。</span></span></div>
<div style="margin: 0cm 0cm 0pt 39pt; text-indent: -21pt"><span style="font-size: medium"><span style="color: black">2.<span style="font: 7pt 'Times New Roman'">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&