地缘优势，是指由地理位置上的联系而形成的关系。由于对某个地区历史、文化和人群生活习惯

Neap tides occur only ().

A.at a new or full Moon

B.when the Sun，Moon，and Earth are in line

C.at approximately 28-day intervals

D.when the Moon is at quadrature

A.low water neap

B.low water spring

C.high water neap

D.high water spring

Spring tides are tides that ().

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

The smallest tides occur in______.

A．bays

B．open seas

C．inland seas

D．deeper seas

Which statement is TRUE concerning equatorial tides ________．

A.They occur when the Sun is at minimum declination north or south

B.They occur when the Moon is at maximum declination north or south

C.The difference in height between consecutive high or low tides is at a minimum

D.They are used as the basis for the vulgar establishment of the port

Spring tides occur______．

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