Here's my humble opinion, I wish it could helpful for your English. I hope you can adopt my answer.

There are some people who, contented with a single skill or a peep-hole view, never make any progress; they may play some role in the revolution at a given place and time, but not a significant one.

At that age I was only vaguely aware why people used it.

Educational practitioners should be aware of the limitations of rational educational theory itself, namely educational theory is a temporary and personal view.

Meanwhile, the writer also proposes some suggestions on the belonging of the property of Folklore, the content and duration of the property, and the protecting duration.