碳酸铵根的化学式:What is a Friend of the Earth?

What is a Friend of the Earth? a friend in word is never a friend of mine hanging out of my friend--what is the mean? What letter is a part of head? What letter is a part of vegetable? What letter is a kind of drink? what letter is a kind of drink What letter is a kind of drink? he is a friend of mine和he is my friend的区别？ a friend in word is never a friend of mine是什么意思？