单项选择题
A. When do the pilot come? B. When the pilot come? C. At what time will the pilot be available? D. When will the pilot come?
A. Remember: safety first. B. Mind. Safe the first. C. Think of it. Safety is one. D. Think of it. Safety first.
A. Watch your feet! Get hold on the rails. B. Watch your step! Get hold of the rails. C. Watch your step! Get hold to the rails. D. Mind your head! Get hold of the rails.