Question

Are the following statements True or False and how did you work it out
1. 1 + 1 = 0 if 0 + 1 =1
2. 1 + 1 = 0 only if 0 + 1 =1
3. 1 + 1 = 0 is sufficient for 0 + 1 = 1
4. 1 + 1 = 0is necessary for 0 + 1 =1