单项选择题
A.the height of the tide
B.depth of water under the bridge
C.charted vertical clearance at mean low water
D.distance from the water to low steel of the bridge
单项选择题 Attention is called to the fact that in many cases pipelines are not （） and charted depths may be decreased by up to 2 meters．
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 （）.