----- Nội dung dịch tự động từ ảnh ----- Exercise 12: Combine the sentences and decide if they are compound or complex sentences. 1. The air is polluted. People often have breath problems. 2. Factories release harmful gases. Factories release harmful gases. 3. The water in the river is polluted. Fish cannot live in it. 4. Mary wants to help the environment. She participates in beach clean-ups. 3