Tóm tắt nội dung: Câu 1: Hãy đọc kỹ đoạn văn sau và trả lời câu hỏi Throughout the ages people have sought to understand the world around them and to explain it in a systematic way. A system is simply a group of elements which work together to achieve a purpose. Systems can be very large, such as the system of courts and laws we call our 'legal system', or very small, such as the system involved in cleaning your teeth. Systems can occur in nature or be designed by people. The water cycle (described below) is an example...