請指點Grammar

Grammar---passive voice is the subject affected by the passive voice eg:-Rock stars and Someone are the subjects.
On re-arrangement,eg:-Rock stars say the real thrill that they enjoy----is being watched---
Another eg:-Someone who rocks -----is being trained for a job.
Hence the subject performs the action (the active voice) is affected by (the passive voice).

Sentence 1
They enjoy being watched by thousands of adoring fans.

Note that enjoy is a transitive verb, that is, enjoy must be followed by an object. The object can be a noun or a noun phrase.

"being watched by thousands of adoring fans" is a noun phrase, the object of the verb enjoy.

"being watched" is not a verb. "being watched" is a gerund, that is, action word functioning as a noun.

Sentence 2
Someone who is being trained for a job ....

Note that this is not a complete sentence. Let's change the sentence for better explanation.

A trainee is someone who is being trained for a job.

"who" is the subject and "is being trained" is the verb in present continuous tense.