The group of the aged are close companions and many of have known each other for decades

问题补充：

The group of the aged are close companions, and many of have known each other for decades.

A. them

B. that

C. whom

D. what

答案：

(答案→)A. them

B. that

C. whom

D. what

解析：考查并列句，因为两句话之间有and，所以是并列句，用them指代companions，句意：这群老年人是亲密的同伴，他们很多已经认识几十年了。选A。