if 3 years old couldnt speak a sentence consider speech delay?

Maybe your kid is just a bit slow. He might be taking his own sweet time. Try talking to him a lot. Read to him, better still let him hear music or watch kiddie shows like Hi5 and Barney. My kids loved watching these shows and they were all early speakers. If you feel there's a concern with speech delay make an appointment with the Polyclinic and let them assess your child. If they see a need to worry they will refer your kid to see a therapist. All the very best to you.