You must develop the muscles of your speech organs to produce unfamiliar sounds.
所以你必须训练和发展你的发音器官(声带、舌、口、鼻腔等)的肌肉,以便发出陌生的(另外一种语言)声音。
Forest fires are often caused by broken glass or by cigarette ends which people carelessly throw away.
森林火灾时常由破碎的玻璃或人们随手扔掉的香烟头引起。