Question

Where had he kept the ring?(change into passive voice)​

Answer 1

Answer:

${} \huge \underbrace \mathfrak \pink{answer} \\ \tt \: Where \: had \: the \: ring \: been \: kept \: by \: him? \\ \\ \rm \: That's \: it, \: my \: friend.$

Answer 2

Answer:

Active voice : Where had he kept the ring?

Passive voice : Where the ring had been kept by him ?

hope it helps you out.

thanks.