________ the air clean, the government will close some factories in the city.
A.Keep B.Keeping C.To keep D.Kept
—Could you tell me ________ we will go to the concert tomorrow?
—By bus.
A.whether B.why C.how D.when
Mrs. Morris has left for London. She ________ a speech there next week.
A.has given B.will give C.gives D.gave
I invited Joe and Linda to dinner, but ______ of them came.
A.neither B.either C.none D.both
Practice more, ________ you will learn English better.
A.or B.yet C.and D.but
We will go on an outing tomorrow ________ it doesn't rain.
A.until B.while C.unless D.if
