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 （）.

The（）may examine or re-examine the goods or take samples from them straightaway in the absence of the consignee or the consignor whenever it considers this necessary.

（）are liable to be stoten, pilfered or may damaged due to improper handing or stowage.

Banks have no liability for any delay or loss caused by postal or telex failure.

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

拦砂坝

简述拦砂坝的作用。

简述拦砂坝的坝址选择。

简述按结构分，拦砂坝的坝形种类几各自特点。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。