论述河流阶地的三大成因。

冰期水位观测，应观测河道、水库（湖泊）等水体的（）的水位。

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.

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

（）应当根据河道规划制定河道整治计划，定期对河道进行疏浚。对淤积严重以及影响防洪排涝、水系沟通和景观的河道，应当优先安排整治。

河道整治工程应预测评价工程兴建后（）变化对环境的影响。

河道及水工程管理范围内建设项目，必须按照河道及水工程管理权限，经（）或经授权的省级（）审查同意后，方可按照基本建设程序履行审批手续。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。