A.自身對(duì)照B.組間對(duì)照C.歷史性對(duì)照D.隨機(jī)同期對(duì)照
A.肉類B.蛋類C.谷類D.蔬菜、水果
A.4.5×109/LB.4×109/LC.3.5×109/LD.3×109/L