The metal sheet used to imitate thunder must be________．

A．tightly fastened on all sides

B．lying flat

C．both A and B

D．neither A nor B

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

[单选题]Additives （） protective layers on metal surfaces guarding them against corrosion.A . damageB . formC . dissolveD . contaminate

[单选题]The thunder [scared]the little girl who is sleeping in the room.A.frightene

[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]We drop a piece of metal into a jar full of water, the metal will float if it weighs less than______.A． an equal amount of silverB． an equal amount of goldC． all the water in the jar nowD． the water that leaves the jar

[单选题]The cross-head shoes are white metal （）.A . liningB . linedC . madeD . i

[名词解释] 液态金属密封 liquid metal seal

[单选题]The cross-head shoes are white metal lined, grooves being cut horizontally on the face of the white metal to ensure （）.A . an adequate supply of lube oilB . an adequate supply of fuel oilC . an adequate supply of turbine oilD . an adequate supply of

[主观题]请将工作表Sheet1移动到Sheet2与Sheet3之间。

[名词解释] Balance sheet