English grammar error-spotting (evaluate tense and complementizer; select ‘‘No error’’ if correct): ‘‘He wanted to work all night / but we saw that he was completely worn out / and so we persuaded him to stop. / No error.’’

Analysis
All verbs are in a consistent past narrative sequence (wanted → saw → persuaded). ‘‘saw that he was completely worn out’’ is idiomatic; ‘‘worn out’’ functions as an adjective complement after ‘‘was’’. No disagreement or misuse of connectors.

Common pitfalls

• Over-editing to ‘‘had been’’ despite simultaneous state during the seeing.
• Removing ‘‘that’’ unnecessarily; it is optional and acceptable.

Final Answer
No error.