Things are known _when they unite with the oxygen of the air

Things are known _when they unite with the oxygen of the air 英语Things are known ______ when they unite with the oxygen of The ___ of oxygen in the air rises, and at last the air beco We ____ in oxygen in the air When we breathe,the oxygen in the air（） with our blood and g As is known,the oxygen we breathe in mixes with our blood an how are the things with to be content with things as they are; to take things as the The best things in life they are They concern the common things of life and are the stock in they concer the commom things of life,and are the stock in t For the most par,they are the kinds of things that we can be