Wǒ zhīdào běijīng zài nǎlǐ

The correct one is "Wo zhi dao Beijing ZAI (fourth tone) na li". "zai" kind of acts like 'at'. So translated would sound something like "I know where Beijing is at" Hope it helps (:

Wo Zhi Dao Bei Jing Zai Na Li) 我 知 道 北 京 在 哪 里

it's better to specify 我 已经 知道 北京市 在哪里。 = wǒ yǐ-jīng zhī-dao Běi-jīng-shì zài-nǎ-li.

Yes but there are some local processing is not very good According to your meaning I know where is Beijing Ha ha ha, I can clearly tell you in China I know where Beijing is your topic Between a Chinese oh