单项选择题 Attention is called to the fact that in many cases charted depths may be decreased by up to （）.

单项选择题 At last，the palm trees that fringe the natural harbor of Port Aloahoa come into view on the horizon lit by the setting sun.The meaning of this sentence is that （）.

单项选择题 As these features are not all charted，special caution should be exercised （） vessels navigating in the vicinity.