What work (if any) is suitable for old people and what work is unsuitable for them?
I think old people are suitable to take care of kids. Nowadays, young couples
are busy with their work, and they don't have much time to look after children.
Those old people, if physically capable, are surely the best ones to take care
of their grandchildren. However, some manual work is unsuitable for them to
do, for example, carrying a box of water to upstairs.