Answers

2016-06-15T20:40:23+08:00
2016-06-15T20:44:11+08:00
Its from our body that circulates everytime we do a respiration. We inhale oxygen and when it circulates through our respiratory system carbon dioxide will came out when we exhale because our body needs oxygen not carbon dioxide but we have it in our body normally to be exchange at oxygen when doing respiration and as well as the plants that needs carbon dioxide to produce oxygen for us and we do as well for them.
0