18. How many types of triliteral verbs with increase letters are there?
19. How many types of quadriliteral verbs with increase letters are there?
20. Why are letters added to the verb?
18. There are three types of triliteral verbs with increase letters. First, triliteral verbs with one increase letter: فَعَّلَ یُفَعِّلُ ، أفعَلَ یُفعِلُ ، فاعَلَ یُفاعِلُ. Second, triliteral verbs with two increase letters: تَفَعَّلَ یَتَفَعَّلُ ، تَفاعَلَ یَتَفاعَلُ ، اِفتَعَلَ یَفتَعِلُ ، اِنفَعَلَ یَنفَعِلُ ، اِفعَلَّ یَفعَلُّ. Third, triliteral verbs with three increase letters: اِستَفعَلَ یَستَفعِلُ ، اِفعَوعَلَ یَفعَوعِلُ.
19. There are two types of quadriliteral verbs with increase letters. First, quadriliteral verbs with one increase letter: تَفَعلَلَ یَتَفَعلَلُ. Second, quadriliteral verbs with two increase letters: اِفعَنلَلَ یَفعَنلِلُ ، اِفعَلَلَّ یَفعَلِلُ.
20. Increase letters are not added to a verb unless to change the meaning of the verb. For example: أفعَلَ and فَعَّلَ are to convert the verb into the transitive form as in أکرَمَ. فاعَل and تفاعل denote a form of dual participation as in شارکتُهُ. تفعّل is to make the فعّل reflexive as in عَلَّمتُهُ فَتَعَلَّمَ. انفعل and افتعل are to make the فَعَلَ reflexive as in نَثرتُهُ فانتَثَرَ. افعلّ is used with an adjective as in احمَرَّ. استفعل denotes asking for something as in استَغفَرَ. تفعلل is to make the فعلل reflexive as in دَحرَجتُهُ فَتَدَحرَجَ. All of the other forms are used for emphasis.