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【单选题】
绘制组合体三视图时,"长对正"指的是( )A.
主视图和俯视图
B.
主视图和左视图
C.
俯视图和左视图
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【单选题】Which of the following modulations is for the VHF radio telephone?
A.
G3E
B.
F3E
C.
G2B
D.
F1B
【简答题】Which of the following radio installations isnot required by ships when sailing in sea areaA2?A. VHF. B. MF. C. EPIRB. D. HF
【单选题】Which of the following facts from the selection best supports the statement that the radioactive waste is an unsolved problem?
A.
We have already generated over 10,000 tons of nuclear waste.
B.
Radioactivity could be released into the environmental from activities related to mining and processing nuclear fuel.
C.
Only a part of nuclear fuel is fissionable.
D.
A location for stainless steel tanks containing 'high-level liquid waste' mixed with molten glass has not been found.
【单选题】The following radio communication systems are used in the GMDSS except( )
A.
the Inmarsat system
B.
VHF MF and HF terrestrial systems
C.
the COSPAS-SARSAT system
D.
the FLAG SIGNAL systems
【单选题】Once ARQ communication with the coast radio station has been establ/shed, which of the following exchanges will most likely take place?
A.
The vessel then requests the coast radio station's selcall so that communication can be set up on the appropriate working channel. ’
B.
Since communication has akeady shifted to the working channel, the vessel then transmits the subscriber number and text of the message to be sent for the coast radio station to store and forward.
C.
After exchanging answerbacks with the vessel, the coast radio station transmits.c GA+"．
D.
After exchanging answerbacks with the coast radio station, the vessel transmits“GA+”．
【单选题】Which of the following characteristics of radio galaxies is mentioned in the passage?
A.
They are a type of elliptical galaxy.
B.
They are usually too small to be seen with a telescope.
C.
They are closely related to irregular galaxies.
D.
They are not as bright as spiral galaxies.
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