单选题Before entering the chain locker，you should（）.A have someone standing byB make sure there is sufficient air within the lockerC de-energize the windlassD All of the above

Which statement about entering into a tank which has been sealed for a long time is TRUE ________．

A.The tank should be tested only once to ensure the oxygen content is at least 14% before entry

B.The tank must be tested at frequent intervals to ensure that hazardous gasses have not regenerated

C.The tank need not be tested for oxygen content if it is ventilated for more than 24 hours

D.If the oxygen content tests at less than 12% you should wear an approved gas mask

The perforated，elevated bottom of the chain locker，which prevents the chains from touching the main locker bottom and allows seepage water to flow to the drains，is called a ______．

A.cradle

B.draft

C.harping

D.manger

You should deposit a certain amount of money with a bank before you buy a house.

A．Right

B．Wrong

C．Doesn't say

The bypass valve on a self-contained breathing device should be opened if ______．

A.You are entering a space containing poisonous vapors

B.You are entering a space containing explosive gases

C.The regulator of the breathing apparatus malfunctions

D.The face piece of the breathing device is too tight

The opening in the deck beneath the anchor windlass that leads to the chain locker is the ______．

A.Hawse pipe

B.Fall pipe

C.Drop-pipe

D.Spill pipe

What can cause a lack of oxygen in a chain locker ________．

A.Absorption

B.Osmosis

C.Evaporation

D.Oxidation

Before entering a fuel tank that has been cleaned, it should be checked with an oxygen indicator and a/an ____.

A.Orsat apparatus

B.flame safety lamp

C.Halide torch

D.combustible gas indicator

Before letting the anchor go, you should check that the ______.

A.chain is clear

B.anchor is clear of obstructions

C.wildcat is disengaged

D.All of the above