You have failed two tests. You’d better start working harder, ____ you won’t pass the course.
A.and B.so C.but D.or
—Did you return Fred’s call?
—I didn’t need to ____ I’ll see him tomorrow.
A.though B.unless C.when D.because
Many children， ______ parents are away working in big cities，are taken good care of in the village.
A.their B.whose C.of them D.with whom
____ parents say and do has a life-long effect on their children.
A.That B.Which C.What D.As
—She looks very happy. She ______ have passed the exam.
—I guess so. It’s not difficult after all.
A.should B.could C.must D.might
____ he had not hurt his leg, John would have won the race.
A.If B.Since C.Though D.When
