1. A traffic light is red only if vehicles stop and pedestrians cross. Vehicles do not stop. Therefore, the traffic light is not red or pedestrians do not cross. 2. Daily exercise is a sufficient...

1. A traffic light is red only if vehicles stop and pedestrians cross. Vehicles do not stop. Therefore, the traffic light is not red or pedestrians do not cross.

2. Daily exercise is a sufficient condition for not gaining weight. You do not exercise daily only if you are unhealthy. You are healthy. Therefore, you do not gain weight.