A trail is a route along a series of paths or roads, often one that has been planned and marked out for a particular purpose.
(有特定目的的) 路线; 路径 The hurricane left a trail of destruction behind it. 飓风过后满目疮痍。
If you trail someone or something, you follow them secretly, often by finding the marks or signs that they have left.
跟踪 The hounds were following the fox's trail. 猎犬追踪着狐狸的气味。