Put it on a mirror shelf with a small light at the top, jewelry is not a clause, it is called the non-predicate structure of verbs, the past participle of verbs is passive, and jewelry is put on the mirror.

The children are trying to water the saplings, and sweat is shining on their foreheads. This is not a clause either. This is a complex sentence, that is, a complex sentence composed of two simple sentences. If you add when in front of the child, it is an adverbial clause of time.