生长家畜全价日粮中矿物质饲料大约占（）。
A.7%
B.5%
C.3%
D.2%
参考答案：D
--Tony, come down and help me with the heavy box!
-- Come on! I _____ all day long．Get Peter to do that!
A．work
B．had been working
C．had worked
D．have been working
如何识读工艺流程图？
