杆的箍线应用（）毫米钢线缠绕，搭接头处应用压头或卡钉封固。
A.2
B.4
C.6
参考答案：B
Now people can _______ with their friends far away by e-mail, cellphone or letter. [ ]
A. keep on
B. keep in touch
C. keep up
行导管相关性血流感染监测时，拔除导管后，将导管尖端（）做血培养。
A.4cm
B.5cm
C.8cm
D.10cm
