They put up a notice about the event in the school.

他们在学校里张贴了活动通知。

My headteacher had already put up a notice: Lost at school.

我的班主任已经贴了一个通知:在学校迷路了。

May be necessary to put up a notice saying keep off . Another thing.

也许还需要竖立一个布告牌，写上“不得践踏”。还有一件事。