that al- is not prefixed to verbs. Therefore, when al- is prefixed to a noun, there is no longer any danger of the noun being confused with a verb, and so the nunation is no longer needed. Hence, no noun has both al- and nunation simultaneously. However, there are some types of nunation whose purpose is not to differentiate between nouns and verbs. Such types include (a type of nunation converted from an alif at the end of poetic couplets) and (a type of nunation used to maintain the metre of a poem). An example of the first type in conjunction with al- is found in the following couplet of poetry: And an example of the second type in conjunction with al- is found in the verse below: Necessary prefixation There are some nouns that are invariably seen with al-. Examples include the relative pronoun al-ladhī (that/which/etc). Al- on numbers Al- may be prefixed to the first part of a number between 11 and 19. For example, aḥada ‘ashar (eleven) may be read as "al-aḥada ‘ashar". In the case of a compound number (21-29, 31-39, ..., 91-99), al- may be prefixed to both parts. For example, wāḥid wa-‘ishrūn (twenty-one) may be read as "al-wāḥid wa-al-‘ishrūn". Al- on participles When al- is prefixed to a participle, it acts like a relative pronoun. For the purposes of this rule, participles include (the active participle), (the passive participle), (another participle in Arabic), etc. For example, . This is translated as “I passed by the man who was riding his steed” as opposed to something like “I passed by the rider of his steed.” Consequently, all the rules of Arabic relative pronouns and their clauses will apply here. It is widely accepted in Arabic grammar that a participle can carry tense. This tense, however, is typically limited to the present and future. But when we use the above construction, the past can be connoted by the participle as well due to the nature of relative clauses. For example, one may say (I passed by the man who was riding his steed yesterday). Some grammarians, however, say that it is only the past that can be connoted in this construction; the option of connoting the present and future is no longer available. And others say that no tense at all can be connoted. Effects of al- on grammatical case Al- has very few contributions to