return trace的用法和樣例：
例句
- But in the counties I visited, even including those that were formerly bandit-ridden, there was no trace of bandits.
至於土匪，則我所走過的各縣全然絕了跡，哪怕從前是出土匪很多的地方。 - Because any trace of water would evaporate in the Sun's heat, astronomers do not believe that debris trails contain ice.
由於水在太陽輻射下會汽化，天文學家們認為這裡的尾跡並不含有冰。 - Do you have a return ticket to Taiwan?
是否有台灣回程機票？ - They will send you tickets by return of post.
他們將在回程郵件中把你的票送來。
