单项选择题 In the Northern Hemisphere you are caught in the dangerous semicircle with plenty of sea room available. The best course of action is to bring the wind on the（）.

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（）.