it is high time that we ____something about the polluted river,or else it will become harder and harder for people here to breath A.would do B,did C.do D.will do

it is high time that we ____something about the polluted river,or else it will become harder and harder for people here to breath A.would do B,did C.do D.will do
it is high time that we ____something about the polluted river,
or else it will become harder and harder for people here to breath A.would do B,did C.do D.will do

it is high time that we ____something about the polluted river,or else it will become harder and harder for people here to breath A.would do B,did C.do D.will do
b,虚拟语气.