单选题The characteristic of a lighted cardinal mark may be （）.A very quick flashingB flashingC fixedD occulting

If the acquisition symbol flashes three times when acquisition is attempted，it may be possible that the acquisition symbol ________ over the navigation mark．

A.is not positioned properly

B.is not a fixed position

C.is not at a position fixed

D.is a wrong position

A survey (special purpose mark) buoy ______.

A.must be lighted

B.may have a flashing red light

C.may have a fixed white light

D.None of the above

基数效用（Cardinal utility）

A cardinal mark showing an uninterrupted quick-flashing white light indicates the deepest water in the area is on the ______.

A.north side of the mark

B.west side of the mark

C.east side of the mark

D.south side of the mark

The characteristic of a lighted cardinal mark may be ______.

A.very quick flashing

B.flashing

C.fixed

D.occulting

You are loading in the winter in Albany，N.Y.，for a voyage to a port governed by the tropical load line mark. Which of the following statements is TRUE? (Hydrometer reading in Albany is 1.000)

A.You may not exceed the winter load line mark when you finish loading except for the burnout to sea

B.You may calculate the burnout necessary to reach the tropical zone and load extra cargo to compensate

C.The freshwater allowance and burnout to sea may be subtracted from the required freeboard in Albany

D.You may load to the winter mark less the fresh water allowance if you will be at the tropical mark upon arrival in the tropical zone

An analog signal's characteristic quantity representing data may 66). at any instant, any value within a continuous(67). For example, an analog signal may follow continuously the values of another physical quantity representing data.A discrete signal is composed of(68)elements in time, each element having one or more characteristic quantities which can represent data. Examples of characteristic quantities are amplitude, waveform,(69), and position in time. A digital signal is a special case of discrete signals, in which data are represented by a(70)number of well-defined discrete values that one of its characteristic quantities may take in time.

A．acquire

B．collect

C．assume

D．fetch