当探测到前向邻居节点为空时，扩大前向区域的角度，以此来扩大前向区域的范围，直到找到一个符合要求的节点。

When the prior neighbor node is empty, widen the Angle of the prior region in order to widen the scope of prior region until find out a satisfied node.

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受害人的家庭把怒火泼向警察。因为就在三天前，杨家钦用斧头砍伤了邻居，但他却没有被拘留。

The victims' families have focused their rage on the police. Three days earlier, Mr. Yang had struck a neighbor in the head with an ax, but was not detained.

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