Sentence forming

My 2 yr old ds is amazing at everything else, he sprints away from me when I want to potty train him, he knows letter recognition, shapes recognition, he can correlate that A is apple upon seeing "A" he can say bye bye, even sing along the songs example sesame street, daniel the Tiger,  just want to get him to let me know what he wants kinda thing, he is an einstein in all other things though.