Indicate whether the following principles are true or false and why.
1. If having feature $F$ is a sufficient condition for having feature $G$, then having feature $G$ is a necessary condition for having feature $F$.
2. If having feature $F$ is a sufficient condition for having feature $G$, then lacking feature $F$ is a necessary condition for lacking feature $G$.
3. If lacking feature $F$ is a sufficient condition for having feature $G$, then having feature $F$ is a necessary condition for lacking feature $G$.
4. If lacking feature $F$ is a sufficient condition for having feature $G$, then lacking feature $F$ is a necessary condition for having feature $G$.
5. If having either feature $F$ or feature $G$ is a sufficient condition for having feature $H$, then having feature $F$ is a sufficient condition for having feature $H$.
6. If having either feature $F$ or feature $G$ is a sufficient condition for having feature $H$, then having feature $G$ is a sufficient condition for having feature $H$.
7. If having either feature $F$ or feature $G$ is a sufficient condition for having feature $H$, then not having feature $F$ is a necessary condition for not having feature $H$.
8. If having both feature $F$ and feature $G$ is a necessary condition for having feature $H$, then lacking feature $F$ is a sufficient condition for lacking feature $H$.
9. If not having both feature $F$ and feature $G$ is a sufficient condition for having feature $H$, then lacking feature $F$ is a sufficient condition for having feature $H$.
10. If having either feature $F$ or feature $G$ is a sufficient condition for having feature $H$, then having both feature $F$ and feature $G$ is a sufficient condition for having feature $H$.