他不明白人们是怎么用纸来买食物和贵重物品的！他还对人们用来燃烧产生热量的黑色石头感到困惑。

He could not understand how people paid for food and valuable things with paper! He was also puzzled by the black stones people used to burn to produce heat.

youdao

外行人的碳水化合物概念一般仅包括食物中能产生热量和脂肪的糖和淀粉，而食品科学家还知道许多摄入的他种碳水化合物。

The layman’s conception of carbohydrates generally involves only the sugars and starches of foods—those that generate calories and fat. The food chemist knows many other types that are ingested.

youdao

这些炉子基本是烧木头的（差一点的话垃圾也可以），可以每天为30亿人提供食物、产生热量。

These stoves generally run on wood (or, worse, rubbish) and are the go-to source of heat and food preparation for some 3 billion people every single day.

youdao