问题补充:
Black clouds had completely the sun.
A. blocked off
B. broken out
C. blocked out
D. broken off
答案:
A. blocked off
B. broken out
(答案→)C. blocked out
D. broken off
解析:考查词组:A. blocked off封堵B. broken out爆发C. blocked out遮住,挡住D. broken off折断,句意:乌云完全遮住了太阳。选C。