A.when the moon is new or full
B.when the moon and sun have declination of the same name
C.only when the moon and sun are on the same sides of the earth
D.at the beginning of spring when the sun is over the equator
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A.at the start of spring，when the Sun is nearly over the equator
B.only when the Sun and Moon are on the same side of the Earth and nearly in line
C.when the Sun and Moon are at approximately 90°to each other as seen from the Earth
D.when the Sun，Moon，and Earth are nearly in line，in any order
A.have lows lower than normal and highs higher than normal
B.have lows higher than normal and highs lower than normal
C.are unpredictable
D.occur in the spring of the year
A.its velocity in knots
B.direction from which it flows
C.estimated current
D.direction toward which it flows
A.interruption of the normal current flow by the footing
B.elevating in mud-slide zones
C.penetrating rapidly through a hard crust into weaker soils
D.extracting legs from soils with high cohesion
A.pick up speed where the channel widens
B.run slower in the center of the channel
C.hug the inside of a bend
D.cause the greatest depth of water to be along the outside of a bend
最新試題
To make sure of getting the full advantage of a favorable current，you should reach an entrance or strait at what time in relation to the predicted time of the favorable current?（）
Tide is（）in direction ENE.
A wave entering（）is likely to produce bores．
Stand of the tide is that time when（）.
You are anchoring in a river where the current is from one direction only.The best way to lay out two anchors is to have them（）.
Which statement is TRUE concerning equatorial tides（）.
The velocity of the wind，its steady direction，and the amount of time it has blown determines a wind driven current’s（）.
Spring tides are tides that（）.
The steady current circling the globe at about 60°S is the（）.
Tides are superimposed on nontidal rising and falling water levels，caused by（）．