More and more people have realized we won’t have cleaner water to drink unless something ________ soon．

1. A.
   was done
2. B.
   will be done
3. C.
   to be done
4. D.
   is done

More and more people have realized we won’t have cleaner water to drink unless something______ soon．

A．is done          B．will be done          C．to be done            D．was done

More and more people have realized we won’t have cleaner water to drink unless something

            soon.

A．was done         B．will be done      C．to be done       D．is done