农作物肥料的三要素是( )。
A．镁、氨、硅
B．硅、钾、磷
C．镁、磷、钾
D．氮、磷、钾
参考答案：D
---__________?
---In a factory.
A．Where does he work
B．Where is he from
C．What does he do
D．What does he like
铅酸蓄电池正极板的材料是经过特殊加工后的（）
（A）PbO2
（B）Pb
（C）PbSO4
（D）PbO
