渗透法能检出的尺寸，一般深约（）um，宽约1um。
A.20
B.10
C.5
D.2
参考答案：A
Sometimes walking is even _____ than driving during the busy traffic time.[ ]
A. fast
B. faster
C. slow
D. slower
中梁下翼板、腹板腐蚀深度大于（）时，堆焊或补平形补强板。
A、0.2
B、0.3
C、0.4
D、0.5
