In general，the most effective period for observing stars and planets occurs during the darker limit of（）.

A、A.sunset

B、B.civil twilight

C、C.nautical twilight

D、D.astronomical twilight

查看正确答案

更多“In general，the most effective period for observing stars and planets occurs during the darker limit of（）.”相关的问题

第1题

[单选题] The use of sinking and dispersing agents for the removal of surface oil is （）.

A、the most common method used in the United States B、too expensive for common use C、generally safe to sea life D、generally harmful to sea life

点击查看答案

第2题

[单选题] The SOLAS Convention in its successive forms is generally regarded as the most important of all international treaties concerning the （） of merchant ships.

A、pollution B、economization C、safety D、efficiency

点击查看答案

第3题

[单选题] Which of the following statements about general cargoes is not correct?（）

A、General cargoes are neither liquid nor solid bulk cargo B、General cargoes are packaged hazardous cargoes C、General cargoes are also called breakbulk cargoes D、General cargoes are mostly carried on container ships now

点击查看答案

第4题

[单选题] The Great Barrier Reef is included on the World Heritage list because（）

A、it has the most beautiful seascape in the world B、it has the greatest number of islands in the world C、it has the most diverse and complex marine life in the world D、it has the longest coast in the world

点击查看答案

第5题

[多选题] Which three tasks can be automatically performed by the Automatic Data Optimization feature ofInformation lifecycle Management (ILM)?（）

A、Tracking the most recent read time for a table segment in a user tablespace B、Tracking the most recent write time for a table segment in a user tablespace C、Tracking insert time by row for table rows D、Tracking the most recent write time for a table block E、Tracking the most recent read time for a table segment in the SYSAUX tablespace F、Tracking the most recent write time for a table segment in the SYSAUX tablespace

点击查看答案

第6题

[单选题] The velocity of the current in large coastal harbors is（）.

A、predicted in Tidal Current Tables B、unpredictable C、generally constant D、generally too weak to be of concern

点击查看答案

第7题

[单选题] The use of sinking and dispersing chemical agents for removal of surface oil is（）.

A、the most common method used in the United States B、too expensive for common use C、generally safe to sea life D、authorized only with prior approval of the Federal On-Scene Coordinator

点击查看答案

第8题

[单选题] In modern times，the work of stowage is generally deputed to stevedores，but that does not generally relieve the shipowners（）their duties even though the stevedores are，under the charter-party，to be appointed by the Charterers．

A、to B、by C、in D、of

点击查看答案

第9题