主会场、分会场的英文怎么说？

主会场 main centre 或 main meeting-place
它不仅是体育场——还是奥运会的主会场，那里还有很多其他的建筑设施。
It's not just the stadium – it's the main centre for the Olympics, with lots of other things there too.

原以为主会场的大背景会更吸引人....
I thought originally that the great background in the main meeting-place will be more attractive....

分会场 Branch meeting place

落成典礼 inaugurating meeting

落成仪式 ceremony

main venue
branch venue