People working 10 or 11 hours a day are more likely to suffer from heart problems than who

问题补充：

People working 10 or 11 hours a day are more likely to suffer from heart problems than who go off duty after seven hours．

A. those

B. that

C. these

D. them

答案：

(答案→)A. those

B. that

C. these

D. them

解析：“每天工作10或11小时的人比上7小时的人更可能患心脏病。”比较的对象要一致，People是复数形式，应该用代词that的复数形式those。故选A。