"Gareth and Ceri Lingo were caught by Mr Lingo."
Translation:Gaeth Gareth a Ceri Lingo eu dal gan Mr Lingo.
I find this interesting - I wasn't sure you could put 'eu' after 'gaeth'. I thought it would have to be either 'gaethon gareth a ceri lingo eu dal' or 'gaeth gareth a ceri lingo ei dal'.
You only ever use the third person plural ("they") form of the verb if you actually say nhw "they". Otherwise, you use the third person singular ("s/he") form: here that's gaeth.
Gaeth Ceri ei dal "Ceri was caught"
Gaeth hi ei dal "She was caught"
Gaeth Gareth a Ceri eu dal "Gareth and Ceri were caught"
Gaeth y plant eu dal "The kids were caught"
Gaethon nhw eu dal "They were caught"