Ok, thanks for your help. So "dou" can be used as "also", "all" and "both". It should be added to the Chinese translation of the following sentences: We are all... We are both... I've been to xxx, too. Right? Again, thx for your help!!!

We are westerners. = O dei hai sai yan.我哋係西人 ( alternative for 西人:外國人ngoi6 gwok3 jan4) We both are westerners. = O dei leung go dou hai sai yan.我哋倆個都係西人 The three of us are westerners. = O dei saam go dou hai sai yan.=我地其中3個其中係西人 O dei gei1 zung1 saam go dou hai sai yan (say you are a group of 5, but only 3 out of 5 are westerners, the remaining are not) All of us are westerners. = 我地全部都係西人 O dei cyun4 bou6 dou hai sai yan To my understanding (without any formal training in cantonese at school), I think "dou"都 has wide meaning in cantonese, it includes but not limited to:"too" , "all", "same result" 你去過法國, 我都去過法國 (You have been to France, I have been to France too) 我地都係外國人(All of us are westerners) 你唔講我都知(I know it even you do not say it) I think no problem to just say: O dei leung go hai say yan without "dou" , dou is just for stressing "both" in this scenario, if you say we as one unit, I think it's okay without dou ^^

no, you didn't get it right. "dou" doesn't necessarily follow quantities. in english, you distinguish "both" and "all". but in cantonese or mandarin, if the person you talk to knows how many person you are refering to ,我地都係西方人（O dei dou hai sai fon yan）=We both are westerners/The three of us are westerners/All of us are westerners.Of course you can add quantities in front of "dou" too, it is also right. in this case it will be :我地两个都係西方人(O dei leung go dou hai sai fon yan.) =We both are westerners，我地三个都係西方人(O dei saam go dou hai sai fon yan. )=The three of us are westerners，我地全部都係西方人(O dei chuin bou dou hai sai fon yan)=All of us are westerners. i am a native speaker, we never learn this local language in school systemetically ,the pronounciation i added may not be right. i just wanted to point it out where you should add something. hope it can be a little help for you .

All of us are westerners = Ngo dei hai sai yan 我地係西人. We all are also westerners then you add "dou" 都 = also.我地 都 係西人 The best way to know if "dou" is needed is when "also" is used.