placidly       
adverb uk/ˈplæs.ɪd.li/ us/ˈplæs.ɪd.li/
 宁静地;平和地
in a calm way
  Eleanor smiled placidly. 埃莉诺温和地笑了笑。 
 The man suddenly became quiet, then placidly gave himself up.  那男人突然安静下来,然后平静地投降了。 
 See: placid
 - More examples
 - The evening had begun placidly, with families doing their food shopping and eating ice cream to beat the Baghdad heat.
 - The network of drainage culverts flowed placidly beside and under empty streets.
 - A policeman's horse placidly nibbles a blade of grass.
 - "No," Ellen said placidly.