问题 名词解释

牙周致病菌

答案

参考答案:牙周致病菌 牙菌斑中绝大多数细菌为口腔正常菌丛,是人类与微生物长期共存进化过程中形成的微生物群,对宿主无不良影响,仅少数细菌(约30种)与牙周病的发生、发展密切相关,在各型牙周病的病损区,常可分离出一种或几种优势菌,它们具有显著的毒力或致病性,能通过多种机制干扰宿主防御能力,具有引发牙周破坏的潜能,称之为牙周致病菌。

阅读理解与欣赏

阅读《田野上的白发》,回答问题。

田野上的白发

刘益善

  ①母亲50岁后,头发日渐白了。先是两鬓,后来是额前,再后来满头芦花,让我们感到心痛。

  ②父母都不愿离开家,家里有猪鸡水牛,有房子和责任田,上高中的小弟还要人照顾,患不治之症的父亲不能劳动,里里外外都是母亲一人操持,她头发还有不白的么?  

  ③4月的一个晚上,我搭同事的便车回老家,想看看父母和小弟。到家时已是晚上11点多了,家里没人,门上挂了锁。奇怪,这么晚了,父母到哪去了呢?天气乍暖还寒,夜风吹过,身上有阵阵凉意。朝远处田野望去,怎么回事呀?空旷的田野上有灯火闪烁,不时有阵阵敲盆的声音传来,我信步朝田野走去。

  ④到了田边,我像被人使了定身法一般,呆立在夜色里。只见母亲一手提着脸盆,一手握根棒子,敲击着,发出当当的声响。母亲在田埂上蹒跚地转悠,田埂角上放着盏马灯,灯火如豆。田里是平整的秧圃,依稀可见撒下的稻种已经抽出嫩芽。母亲身上披了件破棉袄,手里不停地敲击着。我叫了声母亲,母亲见是我,停了下来,脸上溢着慈祥的微笑。在母亲停下的当儿,有一群黑乎乎的东西冲向秧圃。母亲一见,立刻又敲起来,那黑乎乎的便逃散而去。母亲说,今年是少有的奇怪,撒下的稻种一个晚上便被老鼠吃得精光。没有办法,大家只好日夜在田边守着。母亲告诉我,父亲被姐姐接去了,小弟住校,星期天才回,她已经在田边守了三个昼夜了。  

  ⑤母亲和我说话,手里还在敲盆,沿着田埂蹒跚而行。我跟在她后面,心里沉沉的。母亲,您该休息了,把田退了吧!您劳作了一辈子,难道不该享一享福么?我知道,我是劝不动母亲的,她离不开她的田野。平时我们劝她,她都说:你们不要管了,这田是不能退的,我做一天算一天,也好照料你爹和你弟。

  ⑥那个夜晚,我陪着母亲在田野上敲盆赶鼠。母亲的身影在田埂上晃动着,夜色里,只有母亲的白发看得清楚。夜风吹着,母亲的白发在田野上飘拂,飘拂,飘拂出我一脸泪花,飘拂出我又一段回忆。

  ⑦父亲病倒时,正是乡下大忙季节。母亲忍着悲痛,半夜里起来拔好秧,运到水田里。一早回家服侍父亲吃药,再赶到田里插秧。一大块白晃晃的水田里,只有母亲孤单的身影在移动。随着母亲身影的移动,水田里嫩绿的秧苗一行行地立起来,整齐匀称,像块绿色的地毯。母亲是高明的织工,织着绿色;母亲是勤劳的春蚕,吐着绿丝。

  ⑧我赶回家帮母亲插秧,到田边时,一块大田,母亲已插完一大半。她太累了,体力不支,已不是弯腰在田里移动,而是双膝跪在泥水里,艰难地爬行。母亲的衣裤没一处干的地方,浑身是汗渍泥水。母亲跪在田里插完一行,又插一行。我含着泪水冲到田里,喊着:妈,您不该这样拼命!

  ⑨母亲见是我,想站起来,努力了两次却未站起。我一把抱起母亲,感到母亲已瘦得皮包骨头。母亲脸上仍是慈祥的微笑,白发被汗水湿透了,沾在额上脸上脖子上。我为母亲拂了拂头发,一阵风吹来,白发在田野里飘拂起来。母亲说:抢季节要紧啦,这秧早插一天,就能多收一成。我没说话,把母亲送回家,就跑到田里,没命地插起秧来。我累得腰酸背痛,但一想到母亲的白发在眼前飘拂,想到母亲跪在田里的身影,便觉得不累了,腰也不酸了。我一口气插完大田的秧,哭了……

  ⑩母亲离开我们三年了,但我忘不了母亲的白发。她的青丝变白发,是岁月的辛劳所染。母亲的白发,装点着故乡的田野,温暖了我的心灵。  

  啊,母亲的白发哟,还在田野上飘拂么!

1.简要说说文中的母亲是一位什么样的母亲。

 ________________________________________________

2.母亲的白发,让“我”“感到心痛”。文中叙述了哪两件让“我”心痛的事?

  ________________________________________________

3.结合语境,对下列句子作简要赏析。

 ①随着母亲身影的移动,水田里嫩绿的秧苗一行行地立起来,整齐匀称,像块绿色的地毯。

 ________________________________________________

 ②她太累了,体力不支,已不是弯腰在田里移动,而是双膝跪在泥水里,艰难地爬行。

 ________________________________________________

4.下列对文中语句的理解和分析不正确的一项是[ ]

A.①段中“后来满头芦花”一句用乡村常见的芦花来形容母亲的白发,突出母亲头发斑白的特征,切合母亲农妇的身份。

B.③段中“空旷的田野上有灯火闪烁,不时有阵阵敲盆的声音传来”一句看似闲笔,实则为后文的情节发展作了铺垫。

C.④段中“在母亲停下的当儿,有一群黑乎乎的东西冲向秧圃”一句,既写出了老鼠的猖獗,又侧面表现出母亲的辛劳。

D.段以“母亲的白发哟,还在田野上飘拂么!”一句结束全文,言有尽而意无穷,含蓄地抒发了作者浓浓的思乡之情。

5.本文着力描写母亲的白发,请简要分析“白发”在文中有哪些作用?

 ________________________________________________

阅读理解

阅读理解。

     About ten men in every hundred suffer from color blindness in some way. Women are luckier; only about

one in two hundred is affected in this matter, Perhaps, after all, it is safer to be driven by a woman!

     There are different forms of color blindness. In some cases a man may not be able to see deep red. He

may think that red, orange and yellow are all shadows of green. Sometimes a person cannot tell the difference

between blue and green. In rare cases an unlucky man may see everything in shades of green-a strange world

indeed.

     Color blindness in human beings is a strange thing to explain. In a single eye there are millions of very small

things called "cones" (圆锥细胞). These help us to see in a bright light and to tell the difference between colors.

There are also millions of "rods" (棒条体), but these are used for seeing when it is near dark. They show us

shape but no color.

     Some insects have favorite colors. Mosquitoes (蚊子) prefer blue to yellow. A red light will not attract

insects, but a blue lamp will. In a similar way human beings also have favorite colors. Yet we are lucky. With

the aid of the cones in our eyes we tan see many beautiful colors by day, and with the aid of the rods we can

see shapes at night. One day we may even learn more about the invisible (看不见的) colors around us.

1. The passage is mainly about _____.

A. color and its surprising effects

B. women being luckier than men

C. danger caused by color blindness

D. color blindness 

2. According to the passage, with the help of the "cones",we can _____.

A. tell different shapes

B. see in a weak light

C. kill mosquitoes

D. tell orange from yellow

3. Why do some people 8ay it is safer to be driven by women?

A. Women are more careful.

B. There are fewer color-blind women.

C. Women are fonder of driving than men.

D. Women are weaker but quicker in thinking.

4. Which of the statements about the color-blind is true?

A. Not all of them have the same problem in recognizing color.

B. None of them can see deep red.

C. None of them can tell the difference between blue and green.

D. All of them see everything in shades of green.

5. We can attract and kill mosquitoes by using a _____.

A. red light

B. yellow light

C. blue light

D. green light