I have been working out how many words there are in the English language with only two letters. Excluding exclamations like Oh! and Ah! the following are what I have come up with :-
am, an, as, at. / be, by, / do, / go, / he, / if, in, is, it, / me, my, / no, / of, on, ow, / so, / ta, to, / up, us, / we.
I suppose I could have added Ma and Pa as well. But even with those two it only adds up to 27. Not many, but then there are only two words with one letter – A and I.