第一部分 翻译

1)In addition to corrosion from the inter-connection of dissimilar metals, galvanic cells are created because of variations in ion concentration, oxygen differential, variance in stress, cold worked metal in contact with the same metal annealed, and heterogeneous soil conditions.

2)It is important to remember that corrosion always takes place at the anode (where current leaves the metal surface and enters the electrolyte) and that no corrosion or a protective effect is experienced at the cathode (where current is received by the metallic surface from the electrolyte).

3)Steel pipes used to transport products such as hydrocarbons, need protection from attack by various corrosive factors in the soil, chemical ions, bacteria, conditions favoring current circulation through the pipe (such as crossing zones of different properties which would induce a “galvanic” effect) or stray currents.

第二部分 听力

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第三部分

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