Plastic deformation is recoverable while elastic deformation is irrecoverable.

第1题

A) ______ deformation is irrecoverable while B) ______ deformation is recoverable.

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第2题

The strength of a thermoplastic polymer such as polyethylene tends to increase after uniaxial deform

ation, because______.

A．cross linking occurs during deformation

B．oxidation occurs during deformation in air at room temperature

C．polymer chains tend to align themselves with the chain axis oriented along the direction of deformation

D．none of the above

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第3题

elastic deformation

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第4题

Rapidly removing elastomeric impression materials will reduce（)A．permanent deformation

Rapidly removing elastomeric impression materials will reduce()

A．permanent deformation

B．tear s~ength

C．setting time

D．syneresis

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第5题

Elastic strain（)A．is strain thatpermanently remains,when the lvadcausing it is removedB．

Elastic strain()

A．is strain thatpermanently remains,when the lvadcausing it is removed

B．occurs below the proportional limit

C．is also known as permammt deformation

D．none of the above

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第6题

A restorative material that has a high proportional limit，compared with one with a lower p

roportional limit，invariably has()

A．greater ductility

B．greater toughness

C．a higher modulus ofelasticity

D．more resistance to permanent deformation

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第7题

Brittle materials have which of the following characteristics（)A．they undergo a lot of

Brittle materials have which of the following characteristics()

A．they undergo a lot of permanent deformation before fracturing

B．they tend to have a very ordered atomic structure

C．they respond poorly to tensile forces

D．A and B

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第8题

Which of the following is not metalline？

A.copper

B.plastic

C.iron

D.aluminium

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第9题

The reader learns that toxic chemicals get into our food________.

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A.when plastic becomes small enough to enter our food chain

B.because other animals are being killed by plastic

C.because plastic does not biodegrade

D.from plastic bags from supermarkets

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第10题

“塑料桶、麻袋、木箱”正确的翻译为( )。

A.plastic drum/gunny bag/wooden case

B.wooden case/plastic drum/gunny bag

C.wooden case/gunny bag/plastic drum

D.plastic drum/wooden case/gunny bag

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第11题

塑性流动（plastic flow)

塑性流动(plastic flow)

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