Define the acronym MSI（）.

单项选择题Deficient oxygen content inside a chain locker can be detected with（）.

A.litmus paper
B.combustible gas indicator
C.oxygen breathing apparatus
D.oxygen indicator

单项选择题Deck beams on a ship are generally spaced at equal intervals and run（）.

A.longitudinally
B.vertically
C.transversely
D.intermittently

单项选择题Day-shapes must be displayed（）.

A.between sunset and sunrise
B.only between 8 AM and 4 PM
C.during daylight hours in any visibility
D.during daylight hours in unrestricted visibility only

单项选择题Daylight savings time is a form of zone time that adopts the time（）.

A.one zone to the east
B.one zone to the west
C.two zones to the east
D.two zones to the west

单项选择题Dacron sails，when not in use，may be damaged if（）.

A.left in the sunlight
B.stowed wet
C.washed with soap
D.folded frequently