问题 多项选择题

采用机械密封时,()是静密封。

A.静环和动环的接触面间的密封

B.静环与端盖之间的密封

C.端盖与泵体之间的密封

D.动环与轴质安监的密封

答案

参考答案:B, C, D

阅读理解

阅读理解。

     In their book Time to Eat the Dog:The Real Guide to Sustainable Living,Robert and Brenda

 Vale say keeping a mediumsized dog has the same ecological impact as driving 10,000 km a year

in a 4.6 liter Land Cruiser.

     "We're not actually saying it is time to eat the dog.We're just saying that we need to think about

and know the ecological impact of some of the things we do and that we take for granted."

     Constructing and driving the jeep for a year requires 0.41 hectares of land,while growing and

manufacturing a dog's food takes about 0.84 hectares-or 1.1 hectares in the case of a large dog

such as a German shepherd.

     Convincing flesheating cats and dogs to go vegetarian for the sake of the planet is a nonstarter,

the Vales say.Instead they recommend keeping "greener",smaller,and more sustainable pets,such as

goldfish,chickens or rabbits.

     The book's playful title,and serious suggestion that pet animals may be usefully"recycled",by

being eaten by their owners or turned into pet food when they die,may not appeal to animal fans.

     Annoying as the idea may be,the question is valid given the planet's growing population and limited

resources,Robert Vale said.

     "Issues about sustainability are increasingly becoming things that are going to require us to make

choices which are as difficult as eating your dog.It's not just about changing your light bulbs or taking

a cloth bag to the supermarket,"he said.

     "It's about much more challenging and difficult issues," he added.

1.The authors gave their book the playful title to________.

A.make it amusing  

B.create a vivid image

C.show writing skills  

D.arouse people's concern

2.In Paragraph 3 the writer mainly wants to tell us________.

A.the amount of consumed land

B.the neglected ecological impact

C.some familiar examples

D.some actual figures

3.Who may not like the idea of "recycling" pet animals?

A.Manufacturers.  

B.Drivers.

C.Animal fans.  

D.The authorities.

4.What do the authors think of living a sustainable life?

A.Challenging.  

B.Inspiring.

C.Inviting.  

D.Touching.

单项选择题