To draw a guard on a sequence diagram in UML 1.x, you placed the guard element above the message line being guarded and in front of the message name.

UML 1 . x中，为了在一个序列图上画一个约束，你把约束元件放在约束的消息线上，消息名字之前。

youdao

He is trying to decide if he should save time for talking to a guard near the X-ray machines when he is appalled-and elated-to see the black-haired girl.

他正在考虑为了节省时间，就跟那个站在金属探测器旁边的保安员谈一下。突然，他眼睛一亮，喜出望外吃惊地看到了那个黑发女人(报纸上会说：“长着一头乌黑秀发的女贼。”)

youdao

Another guard who has been trained as an x-ray operator, complained that he was unable to get through to G4S to find out when and where he was meant to be working, and was once left on hold on the phone for 38 minutes.

FORBES: Report From Inside The Olympic Security Mess: No Schedules, No Uniforms And No Training