单项选择题
---How many revolutions? ---（）.
A. Slow ahead B. Eighty C. Thirty minutes D. Slow
单项选择题 ---Dead slow ahead! ---Reply: （）. ---Report: Engine dead slow ahead.
单项选择题 ---Stand by engine! ---Reply: Stand by engine! ---Report: （）.
单项选择题 Stand by engine. （）
