驾驶机动车上路行驶应当按规定悬挂号牌。

以下关于射频技术的叙述中，错误的是（）。

A．射频技术基本原理是电磁理论

B．射频是条码技术的一种应用

C．射频识别信息具有保密性

D．射频识别标签具有可读写能力

The joke told by Tom made us______, so our maths teacher couldn’t make himself______.

A．laugh; hearing

B．laugh; heard

C．laughing; hear

D．laughed; to be heard

——-We had a good time in dancing at a disco, why didn't you go with us?

——-I ________ there, but my parents didn't let me go.

A．couldn't go

B．failed to go

C．hadn't gone

D．would have gone

电缆桥架有哪几部分组成？