Most of the sentence in English will have atleast one two letter words.

Two letter words are High Frequency Words that appear very frequently. And knowing how to read these two letter words is the first step to learn English Reading. So as soon as I taught phonics to my daughter, I started teaching her reading two letter words like as, to, is …

Tip: Always teach two letter words using letter names,  like you teach sight words but not using phonics.  Below is the list which you can dounload for free.