I think we Thais have this 'how to use and' problem because we are not paying enough attention to grammar (for Thai and hence for English). We don't learn (in school) how to analyze clauses grammatically. Had we learn Pali (the Buddhist language) in school, we would have had a firmer base to learn English (and Spanish and French and Italian and so on). We would have had awareness of time (or tenses), number (plurality), gender, and so on. These details in several aspects could make us better thinkers and learners!