Question

(   ) 2. There      lots of fish in the river in the past，but now the water      so

dirty that we can't see any fish.

A.  are;is

B.  were;is

C.  was;was

D.  is;is

Answer 1

 2. B根据in the past可知是一般过去时，fish在本句表复数,故用were;后面根据mm可知是一般现在时,water作主语用is。故选B。