1. Start / Stop
2. Appear / Disappear
3. Open / Close
4. Enter / Exit
5. Accept / Reject
6. Agree / Disagree
7. Increase / Decrease
8. Advance / Retreat
9. Expand / Contract
10. Assemble / Disassemble
11. Construct / Destroy
12. Unite / Separate
13. Push / Pull
14. Attract / Repel
15. Embrace / Reject