单项选择题
A.starboard bow and make as much headway as possible
B.starboard quarter，and make as much headway as possible
C.port quarter，and make as much headway as possible
D.port bow，and make as much headway as possible
单项选择题 In the Northern Hemisphere the major ocean currents tend to flow（）.
单项选择题 In some river mouths and estuaries the incoming high-tide wave crest overtakes the preceding low-tide trough. This results in a wall of water proceeding upstream，and is called a（）.
单项选择题 In some parts of the world there is often a slight fall in tide during the middle of the high water period. The effect is to create a longer period of stand at higher water. This special feature is called a(n)（）.