How to teach baby to speak

My son is 1y 7m, and have not yet speak or combine any words. Everyday we talk to him, teach him to speak, learn with song, with flash card, with video, teaching him while playing, but still no success. He understand what we are saying, he know the animal sound, he know when the que to roar to the dinasour song, all he can say is na, da, & blue for every color. Is there any ways for me to help him speak?