1.The castanets, which were quite old, had been Melanie's grandmother's.

2.You were always singing when you were little.
3.Three Indian elephants patiently towed the logs that had just been cut.
4.Stay with us as long as you want.
5.The Forbidden City, where China's emperors lived, is enclosed by walls.

Identify clause as independent or subordinate then identify each subordinate as adj or adv

1.The castanets had been Melanie's grandmother's.-Indep
2.You were always singing-Indep
3.that had just been cut-Subord-adj
4.as long as you want-subord-adverb
5.where China's emperors lived-subord-adj

All correct! :-)