memorized 英语900句, and yet couldn't understand simple conversational English when they meet a native English speakers face to face. I met many Chinese scholars in the 80s who had the same problem. They could read and write, but in terms of speaking and listening, they were pretty bad. Of course, that doesn't mean "only spoke 3 English words" is not a drastic overstatement in a grand canyon scale.
Btw, is 英语900句 the "English 900 conversation basic sentences?