钢筋焊接网宜采用CRB550级冷轧带肋钢筋或HRB400级热轧带肋钢筋制作，但不可采用CPB550级冷拔光面钢筋制作。( )
参考答案：错
From the _____ expression on her face, we knew that she was very _____ with the result.[ ]
A. exciting; pleasing
B. exciting; pleased
C. excited; pleased
D. excited; pleasing
低碳钢碳弧气刨的刨槽表面产生硬化层的原因是（）。
A.铜斑
B.合金元素被烧损
C.淬硬倾向大
D.金属被加热到高温后急冷
