供35吨转炉用的本厂废钢（不包括板边），长度应按（）控制。
A、≤600mm
B、≤400mm
C、≤500mm
D、≤300mm
参考答案：B
白炭黑有（）和沉淀法白炭黑两种。
句型转换。
1. He knows a little about Chinese. (对划线部分提问)
_____ _____ does he know about Chinese?
2. Jack's mother gives him ten dollars every day. (对划线部分提问)
_____ _____ _____ Jack's mother give him every day?
3. There is an apple in the picture. (对划线部分提问)
How _____ _____ _____ there in the picture?
Chinese?