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.
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。
3
A leatherback may be able to pick up some body heat by basking at the surface; its dark, almost black body color may help it to absorb solar radiation.