----- Nội dung dịch tự động từ ảnh ----- Choose the best option (A, B, C or D) to complete each of the following questions. Questions: 15. What does the sign mean? A. Don't start the machine without warning people first. Choose the best option (A, B, C or D) to complete each of the following questions. Questions: DANGER B. When you hear a warning sound, the machine C. Be careful because the machine can start at will start. any time. SLIPPERY ICE 16. What does the sign mean? A. You should walk or drive carefully because B. You shouldn't slip over on the ice, so be there is ice on the road. careful. D. People should start the machine automatically. C. Don't go out because the roads are slippery D. The roads are slippery because it is as cold as like ice. Go to Settings to activate Windows. ice.