1.C 马戏表演；马戏团　(a performance by) a travelling group of people and animals who entertain the public with acts of skill and daring
2.C 喧闹的场面　a noisy badly behaved meeting, etc.
3.C 环形广场　a round open area where a number of streets join together

1. circus的基本意思是“马戏表演，马戏团”，是集合名词，当其作主语时，谓语动词可为单数，也可为复数。引申可作“喧闹的场面”解。
2. circus也可作“环形广场”解，常与专有名词连用。

　present〔put on〕 a ～　表演马戏
　three-ring ～　热闹的场面

　The circus is coming here next week.　马戏团下星期来这儿。
　The circus were very good, weren't they?　这个马戏团很不错，不是吗?
　There is seldom circus seen in this city.　在这个城市很少有马戏表演可看。
　The hall was like a three-ring circus until the police arrived to restore order.　警察来恢复秩序以前，大厅内一片喧闹和混乱。
　There is a Piccadilly Circus in London.　在伦敦有个笔卡第利广场。

［词源］拉丁语circus（圆，环）