桥在河里的“倒影”和立竿见影的“影”，从它们的成因来看是不同的，前者是由______形成的，后者是由______形成的．“潭清疑水浅”是说光的______．

We all know that,             , the situation will get worse.     [      ]

A. not if dealt carefully with    

B. if not carefully dealt with    

C. if dealt not carefully with    

D. not if carefully dealt with