Which platform for Beijing?

请问到北京该上几号站台？

From which track does the train leave?

火车从哪个站台出发？

The train for London leaves at 8:20 a.m.,platform 9.

开往伦敦的火车上午8点20分从9号站台开出。

The train leaves from track 5.

火车从5号站台出发。