单项选择题
Coast Pilots and navigational charts are kept corrected and up-to-date by using the（）.
A.pilot charts B.Notices to Mariners C.Tide Tables D.Current Tables
单项选择题 Clouds with the prefix “nimbo” in their name（）.
单项选择题 Clouds form（）.
单项选择题 Clean air standards referred to as “Grade D” apply to compressed air for use in（）.
