It's always bugged me how Ryo was able to communicate with people once he arrived in China. He couldn't have known Chinese because he admits in the first game that he doesn't understand it. How can we plug this apparent plot hole?
Simple: he speaks English. A small percentage of Japanese people speak some English. I'm assuming that number might go up a little for those who live in Yokosuka, which is somewhat Americanised due to the US navy bases. Ryo would be used to seeing English signs and perhaps speaking with Americans stationed there. Though it is strange that Ryo seems unaware of sailors in Yokosuka, he is able to communicate with them in the game (I'm assuming they're American). It's very possible Nozomi taught him some English since she's from Canada. Also, he is able to communicate with Tom, a New Yorker. It seems clear to me that Ryo has been exposed to the North American culture in Yokosuka his whole life, and it's reasonable to assume that he can speak decent English.
In Hong Kong, 46% of people speak English (I'm not sure what this number was in the 80s). Ryo would be able to do OK if he spoke English to this population. Along the way, I bet Ryo picked up a lot of Chinese. The best way to learn a language is to ingrain yourself in that population. I'll bet Ryo was interested in Chinese ever since he tried to translate the Chinese letter in the first game. So, it's possible he was studying Chinese before he even left for Hong Kong. By the time he gets to Guilin in disc 4, he can probably speak decent Chinese.
What do you think of this theory?