My cousin is already 3 1/2 years old but still can't pronounce a complete word. Should his parents bring him to the doctor already?

In my opinion, yes. Ideally, here's the pattern: kids who are a year old should be able to speak at least one-syllable word ("ma" for mama). Two-year olds should be able to speak at least two ("bibi" for baby). So on and so forth. There are kids who aren't really articulate in speaking full words, but have a grasp in what those words really meant. That's a good sign. Identify if your cousin is like that. If yes, probably he is just a late bloomer. You can search for speech exercises for toddlers. But if there's no improvement, have him checked by a doctor.

i have a cousin also, can't pronounce a word in a sentence, what i observed about him, he's not sociable because of watching cartoons .at first I don't understand what he's saying and then I noticed his language is english and our dialect is Ilocano. so there we understand now.

i've read that ideally based on his age, he should be able to talk with comprehension of the words and vocabulary should be relatively wide. You may want to check these baby milestones for further read. http://www.webmd.com/parenting/guide/baby-talk-your-babys-first-words

As per dr. Ong. Kakapanood ng youtube nya. Yung imdicator po sa speech development ng bata is. Pag 1year old po dapat nakakasalita na sya ng 1 word. 2years old mka construct na po sya ng sentence with 2words then pag 3years old po 3words din po yung sentence na masalita nya.

For me, yes. There's no harm in having the kid checked out as early as possible. If there are no problems, then good for everyone. If there is, then it's a good thing that it has already been found out

May mga bata na mahina ang development dahil sa gadgets. Advice your cousin to minimize their child to use gadget and more reading books and blocks.

yun anak ng ofcmate ko ganun din, ni recommend din n mag co nsult sa specialist .. pero nun pumasok na sya ok nmn na.. ( kaka 4 y old lang)

I think so. It is best still to consult an expert regarding these matters so as to know early if there's something wrong.

yes po .. kailangan nya ng assesment sa doctor paramalaman kung bakit hindi pa tuwid ang salita

yes po kasi kung delayed lang masyado na watagal bka may problem