simple sentences consist of only one clause, and most contain a finite verb, although some languages allow sentences with no finite verb, or no verb at all. the finite element may be either a main verb or an auxiliary; a finite auxiliary always co-occurs with a main verb, which is usually non-finite. in English, the finite verb always appears before any non-finite verb, and if there are any auxiliaries, the main verb always follows them. cross-linguistically, non-finite verb fall into two main categories: the infinitive, and participial forms of the verb, which often combine with a spectral auxiliaries to denote verbal aspect.