major grain crop的用法和樣例：
例句
- Encouragingly, a new set of tools is revealing that some of the answers may be found by exploring the origins of the three major cereal crops.
可喜的是，現在藉由一套嶄新的工具來追尋這三大主要糧食作物的起源，或許可以找到一些解答。 - But the real revolutionary potential in this method lies in its power to open up the genetic bottleneck created thousands of years ago when our major crops were first domesticated.
但這套方法真正的革新，是突破了數千年前開始栽培主要糧食作物時設下的遺傳瓶頸。
