1. competition for existence：compensation point of carbon dioxide 二氧化碳补偿点 | competition for existence 生存竞争 | competitor 竞争者
2. vital selection：vital of lungs capacity 肺活量 | vital selection 生存竞争 | vital statistics 生命统计
3. struggle for life：struggle for exsitence 生存竞争 | struggle for life 生存竞争 | strychinin 马钱子碱