OT试验阳性表明（）。
A.隐性感染过结核
B.从未接触过结核
C.隐性感染过肝炎
D.细胞免疫有缺陷
E.体液免疫有缺陷
参考答案：A
如何更换无缝道岔的辙叉、尖轨及伤损钢轨？
In recent years, TCP/IP has also begun to be used by telephone companies to provide faster, cheaper telephone (67)
A. transmitting B. transmited C. transfers D. transmissions
