1. I know what you did last summer.
2. The boy who lives next door is Indonesian.
Apart from having two verbs, the sentences also have subordinating conjunctions, in these cases WHO and WHAT. And both clauses (main clause and subordinate clause) can be divided into subject and predicate.
You can say.. The boy is indonesian( simple sentence). But by adding.. ''who lives next door'' you are just trying to tell your listener more about the boy.So ''who lives next door'' is an adjective clause or adjectival clause.
In a nutshell, all the sentences are simple sentences.