45. (2018江西)The water ________ dark and dirty. It's no longer safe to drink.
A. became  B. has become  
C. will become  D. was becoming
45. B【解析】考查现在完成时。句意：水已经变得又黑又脏，喝它不再安全了。根据句意可知，后句是前句影响的结果，时态应用现在完成时。故选B。