在测定水样的高锰酸盐指数时，需要加入或滴入KMnO4标准溶液三次，其 中第一次加入KMnO4标准溶液的目的是( )。

（）shall be liable for loss of and damage to the Vessel and／or goods arising or resulting from inaccuracies in stating the description，quantity，weight，measurement or contents.

Every deliberate act of wrongdoing by the master or any of the crew against the ship or cargo，without the authorization or privity of the Shipowner or his agent，is（）.

（）, or drum is used for hauling in or letting out the wires or ropes which will fasten the ship to the shore.

A salvor may be（）the whole or part of the payment due under Salvage Convention to the extent that the salvage operations have become necessary or more difficult because of fault or neglect on his part or if the salvor has been guilty of fraud or other dishonest conduct.

The （） is used for hauling in or letting out the wires or ropes.

Vessels must be（）valid certificate of nationality or certificated of registry or license.

When loading or discharging dry mud or cement，crew members should use goggles and（）.

Effects which are dutiable or subject to prohibitions or restrictions should be declared in （）.

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

清洁水样中的六价铬可直接用（）分光光度法测定，如测总铬，用高锰酸钾将三价铬氧化成六价铬，再用该方法测定。当水样中含铬量较高（＞1mg／L）时，采用硫酸亚铁铵滴定法进行测定。