- last post: 01.01.0001 12:00 AM PDT
The flood absorbed Captain Keyes on the Halo orbiting Threshold. That was when the flood learned to speak English, since the flood share a colective mind and share all information from absorbed hosts. As for the Covenant, they had been studying humanity for quite a time. When the Covenant attacked a UNSC frigate 32 years ago, the Covies sent them a warning in English.
[Edited on 6/11/2006]