The collapse of the World Trade Center has put US economy in a difficult .
A. occasion
B. case
C. situation
D. background
网友回答
A. occasion
B. case
(答案→)C. situation
D. background
解析:occasion场合;case情形,案例;situation境遇,境地,形势; background背景。这句话的意思是:世贸大楼的倒塌使美国经济处在了一个困难的境地。