问题
选择题
A vast area north of the Yangtze River__________by the first heavy snow of the new year,causing difficulties to the post-festival road transport.
A．were affected
B．was affected
C．had affected
D．has affected
答案
B
句子的主语为A vast area north of the Yangtze River，所以谓语动词要用单数形式，只能在B项和D项中选择；又因为D项语态不对，所以正确答案为B项。