Original: We all know that most factories would be of no use if there were not clean water supply.

　　Revised: It goes without saying that most factories would be of no use if there were not clean water supply.

　　亮点评析
　　同上例一样，know这样的初级词汇应避免在作文中使用，It goes without saying that…是一个固定结构，意思是“……是不言而喻的”，常在作文中用来引经据典或表明一个尽人皆知的道理，类似的表达还有：
　　An old saying goes that…
　　Proverb goes that…
　　It is universally acknowledged that…
　　It is generally accepted that…