1.In the early 1920's radio stations were requested by the US government to observe silence so transmissions from Martians could be heard.
二十年代早期美国政府甚至要求无线电站监测寂静的太空，以便于截获有可能的火星人的通讯。
2.I am for those students to observe silence for the victims!
我为那些遇难的学生们默哀！
3.We must observe silence in the classroom .
我们在教室里必须保持肃静。