七年级数学作业设计计划

简介：In the spring, summer and autumn, when passing through Xianxian County and heading to Shandong, you have to take the stone bridge. When the ice is the coldest in winter, you may be able to cross the river on the ice. However, the river is low and the banks are high, so it is difficult for the Jianlu army to pass. It is not easy. Walking on the stone bridge is still the fastest and most convenient way. Therefore, the stone bridge must be guarded.