As we know water is very important us.A. of B. to C. on

问题补充：

As we know, water is very important us.

A. of B. to C. on

答案：

解析：of关于，属于； to到，向； on在上面。句意：众所周知，水对于我们很重要。Be adj to对……怎么样。故选B。