1£®I guess you have been asked about the title of your book before.

2£®New inventions like 3D printers have been used to make replacement hearts and bone parts.

3£®I guess someone has asked you about the title of your book before.

4£®People have used new inventions like 3D printers to make replacement hearts and bone parts.

5£®Something bad has happened to him.

6£®The door has opened of itself.

7£®The orphan has been well looked after.