The narrative form looks like the imperfect form, with an additional וַ prefix in front of the imperfect prefix, and with imperfect prefix doubled by a dagesh – וַיִּזְכֹּר. Since the א prefix for the first person singular can’t be doubled by a dagesh, the vowel under the ו changes from patakh to kamatz – וָאֶזְכֹּר. In many cases, especially when there is a weak root letter, there is a stress change in the singular narrative forms: the stress moves forward to the syllable of the imperfect prefix, and there is a shortening of the sounds at the end of the word. In פ”י roots, the final stressed tseirei becomes an unstressed segol: וַיֵּ֫שֶׁב. In ל”ה roots, the final ה drops off and the other two root letters form an unstressed syllable, using one of a few patterns, for example: וַיִּ֫בֶן. When the middle root letter is ו or י, the vowel of the final syllable reduces to a kamatz katan: וַיָּ֫שָׁב.