Tag questions

MohammadReza

Hi,
Could you please tell me what is the correct tag question for the following sentence?

He knows that Tom is younger than Mary , ......... ?

DavidCrosbie

@MohammadReza, tag question have meanings, so more than one question tag is possible.

1. He knows that Tom is younger than Mary, doesn't he?
   The speaker

   • believes that some male person (known to both speaker and hearer) knows thatTom is younger than Mary
   • is inviting the hearer to confirm or agree that this male person person does know this

2. He knows that Tom is younger than Mary, does he?
   The hearer

   • either has just stated that some male person (known to both speaker and hearer) knows that Tom is younger than Mary
   • or has just reported that somebody else has state that some male person (known to both speaker and hearer) knows thatTom is younger than Mary

   The speaker is challenging

   • possibly the validity of the report
     — The speaker doubts that the report was made. Quite probably nobody said that 'he' knows.

   • possibly the substance of the report
     — The speaker doubts that the report is true. Quite probably 'he' doesn't know.

   • possibly the both the validity and the substance of the report

3. He knows that Tom is younger than Mary, isn't he?
   The speaker

   • believes that Tom is younger than Mary
   • assumes that some male person (known to both speaker and hearer) knows thatTom is younger than Mary
   • is inviting the hearer to confirm or agree that Tom is younger than Mary

4. He knows that Tom is younger than Mary, is he?
   The hearer

   • either has just stated that some male person (known to both speaker and hearer) knows that Tom is younger than Mary
   • or as just reported that somebody eelse has state that some male person (known to both speaker and hearer) knows thatTom is younger than Mary

   The speaker
   is challenging specifically the substance of the report — The speaker does not believe that Tom is younger than Mary