Adverbial clauses are subordinate clauses that perform an adverbial function within another clause. The adverbial clauses can be finite or non-finite, but the non-finite forms are much more numerous and, in general, more widely used. Finite adverbial clauses are all marked by subordinating conjunctions. Non-finite adverbial clauses have subordinating suffixes on the verb, and in some cases the verb is also followed by a postposition or noun phrase. The subordinate verb forms that occur in non-finite adverbial clauses are called converbs. In most converbial constructions there is complete freedom for the subjects of the subordinate and superordinate clauses to be either the same or different. The extent to which tense and aspect are marked in non-finite adverbial clauses varies from one type to another. Temporal clauses specify the time of the situation expressed by the superordinate clause by reference to how it relates to the time of some other situation.