Many students in China are learning English. Some of these students are small children. Others are teenagers . Many are adults . Some study at school, others learn by themselves. A few learn English language over the radio, on TV, or in the films. One must work hard to learn another language. Why do all these people want to learn English? It is difficult to answer that question. Many boys and girls learn English at school because it is one of their subjects. They study _ and maths and English. Some people learn English because it is useful for their work. Many people often learn English for their higher studies, because at college or university  some of their books are in English. Other people learn English because they want to read newspapers and magazines in English. _  learn English.
Only teenagers. Only adults. Small children, teenagers and adults. Only small children.