简述选择小学数学教学手段的依据，如何有效地运用小学数学教学手段的条件？

作为小学课程的数学是一种形式化的数学。

教师教育一体化要求教学研究和教学实践一体化，即师范大学和中小学建立伙伴关系，分工协作，师范大学提供理论指导，中小学提供实验基地。

数学是研究现实世界( )的一门科学

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。

数学是研究现实世界（）和（）的一门科学。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。