CO2气体保护焊常用于焊接()材料。
A.碳钢
B.铸铁
C.有色金属
参考答案:A
25.On stepping into the room this morning I was astonished to find the floor covered with______ looked like tiny insects.
A.that
B.something
C.what
D.anything
诊断骨折的主要依据是
A.病史和体征
B.X线检查结果
C.肢体较大的血肿
D.肢体功能障碍
E.全身性表现