多元肥料
参考答案:含有三种和三种以上可标明含量的营养元素的化肥。
—How do you learn English so well?
—______ chatting with my uncle in America-online. [ ]
A. For
B. By
C. In
D. With
司机应了解和掌握各种起重机指挥信号涵义。()
A、正确
B、错误