trees前面加什么冠词为什么

前面加冠词the，例如：

1、They walked through the trees to a second hut， cunningly camouflaged against air surveillance.他们穿过树林来到第二个棚子这个棚子经过巧妙伪装，空中侦察不到。

2、We ran through the trees to Sabden noise of the river was beautiful in my went along the river to the village of Sabden ， and then it began to rain.我们穿过树林来到了萨卜登小溪。潺潺的流水声在我听来十分悦耳。我们沿着河走到了萨卜登村，这时天下起雨来。