质量为m 1="2" kg,m 2="5" kg的两静止小车压缩一条轻弹簧后放在

题型:选择题

问题:

质量为m 1="2" kg,m 2="5" kg的两静止小车压缩一条轻弹簧后放在光滑的水平面上,放手后把小车弹开.今测得m 2受到的冲量是10 N·s,则在此过程中,m 1的动量的变化量是

A.2 kg·m/s

B.-2 kg·m/s

C.10 kg·m/s

D.-10 kg·m/s

考点:动量定理
题型:选择题

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

As we “happen to be” the best creature in the world, it’s our duty to look after other species. Here are some points which might help to protect wildlife.

Join organizations like Greenpeace and World Wildlife Fund. They have devoted themselves to protecting the earth and its animals. Many volunteers join organizations like these and work for the environment. 小题1: 

   小题2:  Don’t buy something made from ivory and things like this. Baby seals(海豹) are hunted for their skin, as it is used to make expensive coats. Don’t buy them.

 小题3: You can write a heartfelt and logical letter to the government stating your ideas about this problem and how it can be solved.

Recycle(回收利用) and reuse. It will reduce the need to have more raw materials to produce something.小题4:  And wild animals’ home will not be destroyed.

Governments should create more safe zones and national parks for wild animals.   小题5:  Governments should apply strict laws to stop hunting.

I hope this post was helpful. Share your views about this issue and let your voice be heard.

A.Let your voice be heard.

B.Stop hunting for pleasure.

C.As a result, fewer trees will be cut down.

D.You can build a bird house and feed local birds.E.Refuse fur coats and medicines made from rare animals

F.You can find some organizations like these and join them.

G. There they will be able to move freely without worrying about hunters.

题型:选择题

I showed an old friend of mine around the city,        surprise, the changes had been so great.

A.whose

B.which

C.to whose

D.to which

题型:选择题

均相酶免疫测定的基本特征是()

A.反应平衡后,抗原抗体复合物中酶活性会发生变化

B.酶标抗原与抗体在固相介质表面形成复合物后,作用于底物成色

C.不用分离B、F即可确定待测物质的含量,表明其反应不易受内源性酶的干扰

D.反应属于非竞争结合,测定的灵敏度较高

E.测定方法较为复杂,且不易用于自动化检测

题型:选择题

蒸压灰砂砖的强度级别分为MU20、MU15、MU10级。

题型:选择题

下列各项中,不属于计算机组成硬件的是()

A.键盘

B.中央处理器(CPU)

C.显示器

D.路由器

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