在有线电视系统前端设备安装中，固定的立柜、立架背面与侧面离墙面净距不应小于（）。

听力原文：W: What's the matter? I've mid you to arrive at 6:...

单项选择题听力原文：W: What's the matter? I've mid you to arrive at 6:30, but now it's seven. Why don't you answer my phone?
M: I'm sorry. I left my mobile phone in the office, so I cannot inform. you of my late arrival. Actually, I started one hour ago, but the traffic jam delayed me for 35 minutes.
Q: When did the man start to meet the woman?
(17)
A．5:55.
B．6:25.
C．6:00.
D．5:30.

听力原文：W: I'm worried about you. You look so pale. Do you...

单项选择题听力原文：W: I'm worried about you. You look so pale. Do you have a headache? You need to take some medicine.
M: A good rest will be more helpful. I was really exhausted at the wedding party last night. I'm sorry that we have to stay in the hotel, because this is the fast day of the honeymoon.
Q: What's the relationship between the man and the woman?
(18)
A．Doctor and patient.
B．Friends.
C．Husband and wife.
D．Boyfriend and girlfriend.

管材表面超声波探伤的计量单位是（）。A.mB.张C.口D.m2

单项选择题管材表面超声波探伤的计量单位是（）。