Walmart，which is one of the largest American supermarket chains， some of its stores open 24 hours on Mondays through Saturdays.(2012·安徽)
A. keeps
B. keep
C. have kept
D. had kept
网友回答
(答案→)A. keeps
B. keep
C. have kept
D. had kept
解析：句意：沃尔玛是美国最大的连锁超市之一，部分店从星期一到星期六24小时营业。根据句中的“is”可知，此处应用一般现在时，主语为Walmart，谓语动词要用第三人称单数，故选A。
易错点拨 本题易错选B或C，错把supermarket chains当成主语。