Can a non-predicate be the subject? Can you give an example?

In non-predicate verbs, participles cannot be used as subjects, but gerunds and infinitives can be used as subjects.

Example:

Smoking is harmful to your health. (Gerund as subject)

It is your duty to keep the classroom clean and tidy. (infinitive as subject)

It takes us two hours to go there by bike. (infinitive is the subject, it is the formal subject, and the real subject is ride there)