root 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.
至于土匪，則我所走過(guò)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.
由于水在太陽(yáng)輻射下會(huì )汽化，天文學(xué)家們認為這里的尾跡并不含有冰。
