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。
it is extremely difficult to estimate the true value of the services which people perform for us.
但要估算别人为我们为所提供的服务的价值却是极其困难的。