To order tickets for the 2016 Riode Janeiro Olympic Games, just call 00982012. It be simpler.
A. must
B. could
C. mustn’t
D. couldn’t
网友回答
A. must
B. could
C. mustn’t
(答案→)D. couldn’t
解析：考查情态动词：could的否定式和比较级连用，表示最高级的含义，句意：为了预定到2016里约热内卢奥运会的票，拨打00982012，再简单不过了。选D。