The bond between humans and livestock is one of the oldest and most vital partnerships in history.
數(shù)學(xué)的本質(zhì)不是使簡(jiǎn)單的事物復(fù)雜化，而是使復(fù)雜的事物簡(jiǎn)單化。
The development of the vital forms under the influence of external conditions is a subject of the highest importance.