All forms of the verb 'to-be' are absent.  I might consider allowing 'to-be' for restricted use, but even then, not for a passive voice.  Tho this might seem unnatural, it does have the advantage of making it a little more difficult to lie.

Using the topic postposition "ka" instead of the accusative "be" on the object has semantically the same meaning as a passive construction. However it fails to fulfill several of the criterias for passive constructions according to the WALS description, so Surang Jumbar is classified as not having a passive construction.

Its "passive voice" doesn't decrease the valency of the verb, and thus doesn't meet the criteria of passive voice listed in WALS.

Focus is accomplished entirely by word order change due to topic fronting. Often, context is necessary to accurately parse a sentence.

In the sentence "Io loum koañ" - man dog bite - 'dog' is in subject position and the meaning is clear, i.e. "The man was bitten by a dog."

In the sentence "Io arch jgeng ngaiyk" - man throw enter ocean - it is unclear without context whether the man threw something into the ocean or was thrown in himself.