Which are true, which are false? Why?
1. Being an integer is a necessary condition for being an even number?
2. Being an integer is a sufficient condition for being either an even or odd number?
3. Being an integer is a necessary condition for being either an even or odd number?
4. Not being an integer is a sufficient condition for not being an odd number?
5. Not being an integer is a sufficient condition for not being an even number?