1. Korea co-hosted the World Cup in 2002 with Japan.
2. Korea hosted the World Cup with Japan in 2002.
3. Korea and Japan co-hosted the World Cup in 2002.
4. Korea hosted the World Cup in 2002 with Japan.
(Are all the same and grammatical?)
They are all grammatically correct but they are NOT the same.
hosted = only one country hosted usually or the World Cup was with Japan and Korea hosted.
co-hosted = now there are two countries or both Korea and Japan were hosts.
Sra