Write full negative sentences. Don’t use short forms and full stops (they are given).

1. Emma and Sally have done gymnastics.

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2. I have met my friend today.

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3. She has sold her car.

1. Emma and Sally have not done gymnastics.
To form the negative sentence, we need to insert the word "not" after the subject "Emma and Sally" and before the auxiliary verb "have", as in "have not". Therefore, the complete negative sentence is "Emma and Sally have not done gymnastics."

2. I have not met my friend today.
Similar to the previous sentence, we need to insert the word "not" after the subject "I" and before the auxiliary verb "have", as in "have not". Therefore, the complete negative sentence is "I have not met my friend today."

3. She has not sold her car.
Again, we need to insert the word "not" after the subject "She" and before the auxiliary verb "has", as in "has not". Therefore, the complete negative sentence is "She has not sold her car."

These negative sentences indicate that the actions described in the original sentences have not taken place.