亚洲91视频,国产91网,久久久久久久久久久久久久久国产,亚洲一区二区三区日本久久九,亚洲日本久久,国产精品久久久99,亚洲欧美一区二

文字稿:

After almost dying out in the 1970s, a kind of whistling language is now undergoing a revival.

Silbo Gomero, as it's known, has become a compulsory subject in one school in Spain's Canary Islands.

The whistling approximates the sounds of the Spanish language.

It can be heard from two miles away, and was used to communicate across valleys and ravines before the arrival of telephones.

Vocabulary 詞匯:

dying out 正在消失的

undergoing a revival 趨于重振

compulsory 必需的，強(qiáng)迫的

approximates 模仿，接近于

ravines 峽谷