问题 选择题

在动物实验中,正确设置对照组不容易.例如,要选择20个完全相似的动物,将其均分为对照组和实验组,就比较困难.那么,进行这种实验时,你认为下列哪种方法最合理?(  )

A.从20个动物中,选出两个相似的动物,一个作为实验组,一个作为对照组

B.将这20个动物随机分成两组,每组10个,一组作为实验组,一组作为对照组

C.将这20个动物分成10对,每对相似,一个放在实验组,一个放在对照组

D.将这20个动物放在一组,先进行实验处理,然后恢复原状观察

答案

对照实验是指在研究一种条件对研究对象的影响时,所进行的除了这种条件不同之外,其他条件都相同的实验.其中这种不同的条件就是实验变量.对实验变量进行处理的,就是实验组.没有处理是的就是对照组.为确保实验组、对照组实验结果的合理性,对影响实验的其他相关因素应设置均处于相同理想状态,这样便于排除因其他因素的存在而影响、干扰实验结果的可能.例如,要选择20个完全相似的动物,将其均分为对照组和实验组,就比较困难.那么,进行这种实验时,可以选出两个相似的动物作为一对,这样将这20个动物分成10对,每对相似,一个放在实验组,一个放在对照组.

故选C.

阅读理解

(2013·高考福建卷,A)When I was 12,all I wanted was a signet (图章) ring.They were the “in” thing and it seemed every girl except me had one.On my 13th birthday,my Mum gave me a signet ring with my initials(姓名首字母) carved into it.I was in heaven.

What made it even more special was that it was about the only thing that wasn’t being “replaced”.We’d been burnt out in fires that swept through our area earlier that year and had lost everything—so most of the “new” stuff (东西) we got was really just to replace what we’d lost.But not my ring.My ring was new.

Then,only one month later,I lost it.I took it off before bed and it was missing in the morning.I was sad and searched everywhere for it.But it seemed to have disappeared.Eventually,I gave up and stopped looking for it.And two years later,we sold the house and moved away.

Years passed,and a couple of moves later,I was visiting my parents’ when Mum told me that she had something for me.It wasn’t my birthday,nor was it Easter or Christmas or any other gift­giving occasion.Mum noticed my questioning look.“You’ll recognize this one,”she said,smiling.

Then she handed me a small ring box.I took it from her and opened it to find my beautiful signet ring inside.

The family who had bought our house 13 years earlier had recently decided to do some redecorations,which included replacing the carpets.When they pulled the carpet up in my old bedroom,they found the ring.As it had my initials carved into it,they realized who owned the ring.They’d had it professionally cleaned up by a jeweler before sending it to my mother.

And it still fits me.

小题1:The underlined word “in” in the first paragraph probably means“________”.

A.fashionable

B.available

C.practical

D.renewable小题2:When she got the ring back,the writer was about ________.

A.13 years old

B.15 years old

C.26 years old

D.28 years old小题3:Which of the following is TRUE according to the passage?

A.The writer’s family moved several times.

B.The writer never stopped looking for her ring.

C.The writer’s ring was cleaned up by the new house owner.

D.The writer lost her ring in the morning when she took it off.小题4:What would be the best title for the passage?

A.My New Ring

B.Lost and Found

C.Lost and Replaced

D.An Expensive Ring

单项选择题