The explosion shook the city center shortly after 1:40 a.m. local time (5:40 p.m.Friday EST), and smoke billowed across the sky.No warning sirens alerted residents, as is protocol here.是什么意思_The explosion shook the city center shortly after 1:40 a.m. local time (5:40 p.m.Friday EST), and smoke billowed across the sky.No warning sirens alerted residents, as is protocol here.在线翻译_英语_读音_用法_例句