1. Richard was anxious to atone for his thoughtlessness.

2. I was hurt by her thoughtlessness.

3. What peeved her most was his thoughtlessness.

4. To do so is based upon prejudice and thoughtlessness.

5. Government is an evil; it is only the thoughtlessness and vices of men that make it a necessary evil. When all men are good and wise, government will of itself decay. Percy Bysshe Shelley 

6. He repented his thoughtlessness.

6. try its best to collect and create good sentences.

7. What women mistake as thoughtlessness is often just diffidence.

8. Everything listened to the singing larks in brooding thoughtlessness.

9. In the sex-war thoughtlessness is the weapon of the male, vindictiveness of the female.

10. I hope not so. Imprudence or thoughtlessness in money matters would be unpardonable in me.

11. But disabled people believe the biggest obstacles they face are mental ones-the prejudices and thoughtlessness of able-bodied people.

12. Though high-pollution drivers often have old cars, the speed-obsessed owners of sports cars are equally guilty of environmental thoughtlessness.

13. At a distance of decades I am staggered by our thoughtlessness in those years.

14. I had no idea that I was saying something that was painful. Please forgive my thoughtlessness.