A person can be on a topic.Logical formLearned from172 sentences. Topics can be theoretical.Logical formLearned from170 sentences. A topic can be narrow.Logical formLearned from170 sentences. Topics can be practical.Logical formLearned from170 sentences. Topics can be wide-ranging.Logical formLearned from169 sentences. A sensitivity may pertain-to a topic.Logical formLearned from167 sentences. Aspects may pertain-to a topic.Logical formLearned from166 sentences. A post can be on a topic.Logical formLearned from166 sentences. Topics may be presented.Logical formLearned from165 sentences. Hundreds can be constituted-of-or-filled-with topics.Logical formLearned from165 sentences. A person may write on a topic.Logical formLearned from165 sentences. Posts can be on a topic.Logical formLearned from164 sentences. A topic can be under discussion.Logical formLearned from164 sentences. Topics can be in history.Logical formLearned from162 sentences. Topics can be in science.Logical formLearned from161 sentences.