Additives （） protective layers on metal surfaces guarding them against corrosion.

[单选题]A．dditives _____ protective layers on metal surfaces guarding them against corrosion.A．damageB．form.C．dissolveD．contaminate

[单选题]Those generally used additives for cooling water are either anti-corrosion oils or inorganic（）.A . gasesB . paintsC . inhibitorsD . detergent

[试题]protective blanket 选择Theatmosphereagainactsourprotectiveblanketon_____[A]stars[B]sun[C]earth[D]space

[名词解释] 保护接地（protective earthing）

[单选题]The main bearing metal is a lining （）.A . inside the bearingB . outside the bearingC . covering the crankshaftD . none of the above

[多选题] 通常MMC（metal matrix composite）（）A .采用高熔点、重金属作为基体。B .要比基体金属或合金的塑性与韧性差。C .要比基体金属或合金的工作温度高。D .要比基体金属或合金的弹性模量低。

[单选题]The metal sheet used to imitate thunder must be________．A．tightly fastened on all sidesB．lying flatC．both A and BD．neither A nor B

[单选题] (74) functions with two layers of protocols．It can connect networks of different speeds and can be adapted to an environment as it expands．(74) A．The hubB．The bridgeC．The routerD．The proxy

[单选题]functions with two layers of protocols. It can connect networks of different speeds and can be adapted to an environment as it expands.A．The hubB．The bridgeC．The routerD．The proxy

[名词解释] 保护线（PE线，protective conductor）