U0259. The principle for using an amateur repeater is:
业余中继台的使用原则是：
Exam tips · 考试提示
Repeaters must stay available for emergencies, so their
uplink/downlink should be idle except for brief necessary contacts (A). B (keep busy) defeats that purpose; C/D
(association notices, student study chat) are not the stated priority principle and can congest the machine.
U0680. Deep space means space at a distance from the Earth
approximately equal to or greater than which of the following
values?
深空（deep space）是指离地球的距离约等于或大于下列值的
空间：
Exam tips · 考试提示
By the ITU/space convention, deep space begins at a distance
of about 2 × 10⁶ km (2 million km) from Earth — roughly
beyond the Moon's orbit (A). The smaller values in B/C/D are within cis-lunar or near-Earth space.
U0681. The orbital inclination of an amateur Earth satellite is defined
as including:
业余地球卫星的轨道倾角（inclination）是指包含：
Exam tips · 考试提示
Orbital inclination is the angle between the orbital plane and the equator, defined at the ascending node (where the satellite
crosses the equator going north) and measured in the counterclockwise (prograde) direction (A). The descending-
node or clockwise variants are not the standard definition.
U0682. The period of an amateur satellite means:
业余卫星的周期（period）是指：
Exam tips · 考试提示
An orbital period is the time for the satellite to return to the
same point on its orbit — equivalently, one full revolution around Earth (A). The intervals over a ground point (B), the
equator (C), or the pole (D) depend on the orbit and are not the definition of the period.
U0683. A geosynchronous satellite means:
地球同步（geosynchronous）卫星是指：
Exam tips · 考试提示
A geosynchronous satellite has an orbital period equal to
Earth's sidereal rotation period (~24 h) (A). B describes a sun-
synchronous orbit, C a polar orbit, and D a sun-synchronous orbit — not geosynchronous.
U0684. A Sun-synchronous orbit satellite means:
太阳同步（轨道）（Sun-synchronous orbit）卫星是指：
Exam tips · 考试提示
A Sun-synchronous orbit precesses so the orbital plane
maintains a fixed angle to the Sun (A). B and C describe a geostationary satellite, and D a geosynchronous satellite — not
sun-synchronous.
U0685. A geostationary satellite means:
地球(geostationary)静止卫星是指：
Exam tips · 考试提示
A geostationary satellite appears nearly fixed over one point on Earth — it is a special case of geosynchronous with a zero-
inclination equatorial orbit (A). B is sun-synchronous, C is polar, and D is wrong because not all geosynchronous satellites are
geostationary (an inclined geosynchronous satellite is not
stationary).
U0686. The direction of a satellite's ascending pass refers to which
part of the orbit:
卫星升轨道（ascending pass）的方向是指轨道的下列区段：
Exam tips · 考试提示
The ascending pass (升轨道) is the arc where the satellite moves
northward, crossing the equator at the ascending node (A). Northward motion is "ascending"; southward is "descending"
(B).
U0687. The direction of a satellite's descending pass refers to which
part of the orbit:
卫星降轨道（descending pass）的方向是指轨道的下列区
段：
Exam tips · 考试提示
The descending pass (降轨道) is the arc where the satellite
moves southward, crossing the equator at the descending node (A). This is the opposite of the ascending (northbound) pass.
U0688. The satellite's period means:
卫星的周期是指：
Exam tips · 考试提示
The orbital period is the time for one revolution around the
Earth (A). B is the spin (rotation) period, C is the revisit interval over a QTH (longer/irregular), and D is a year — none is the
orbital period.