Analysis of air bubbles trapped in fossils, such as in fossil amber, show that our air in earliest times contained about 35% oxygen. Today, the average oxygen content of our air is approximately 20%. In some larger, more polluted cities, oxygen content in the air has been measured at 12 - 15%.
There are 297 words which start with 'pen'. 3 letter words starting with 'pen': pen. 4 letter words starting with 'pen': pend. pens.
what's the word for pen in Italian? come si dice pen in italiano? what does this word mean? cosa vuol dire questa parola? silly isn't the word for it! sciocco non Ã¨ la parola esatta! don't put words into my mouth! non mettermi parole in bocca!