Honorific Verbs conjugation - ～ていらっしゃる vs お + Verb Stem + になる


In book "Genki II", there's no explanation for verbs that **don't have a
special** conjugation, for when to conjugate either to:

  1. 「て Form」 + いらっしゃる
  2. お + Verb Stem + になる

My simple question is when to use the 1st type and when to use the other?

Or do I have the option to select the conjugation for verbs that don't have
the special conjugation?

For example:

読む ー＞

  * お読みになる
  * 読んでいらっしゃる




If you read it carefully in Genki II て＋いらっしゃる is the honorific form for the
て＋いる verb format. Whereas you would use お＋verb stem＋になる when it is not a
continuing action.

