为了保证燃油很好地燃烧，调风器需要将空气分为一次风和二次风。
参考答案：对
He told me he was satisfied with______.
A． all what I said
B．that I said
C．whatever I had said
D．no matter what I said
图A为碳循环示意图，图B是某个食物网，请回答：
碳从无机环境中进入生物群落的途径是（）作用。②中能量流动的特点是（）、（）
