随机监听中的样本是随机选择的，因此样本不具备普遍性。

需重新制作义齿的是（）。

A．正中关系错

B．义齿固位差

C．前牙咬切功能差

D．下颌隆突处压痛

E．说话及大开口时义齿脱落

如图所示的是A、B两种物质的质量m与体积V的关系图象，由图象可知，A、B两种物质的密度、和水的密度之间的大小关系是   

A．>>  

B．>>    

C．>>    

D．>>

我公司承诺对政策性农村住房保险项目实行快速理赔，只要公司和农户签订理赔协议后3个工作日内，公司就向农户发放赔款。

阅读理解

     Compared with their continental counterparts,   children in the UK start school at a very early age.

Our correspondent is not convinced that it gives them any academic advantage.

     My threeyearold son and I went shopping for his school uniform. As he stood in the changing room,

   swamped by even the smallest trousers,   several people commented that he looked too young to start

school. I couldn't agree more. Scarcely will he have blown out the candles on his fourth birthday cake

when I'll be waving him off at the school gates. The poor little man still puts his pants on back to front and

thinks baby pigs come out of eggs. How is he going to cope with literacy and numeracy hours,   let alone

the horrors of school toilets?

     Yes,   I am an overanxious mother but I surely can't be the only person who feels that British children

start school far too young. A research suggests that channelling children into formal learning structures at

such a young age breeds a sense of failure and disaffection that will dog them throughout their school

career.

      The law states that the statutory school starting age for children in the UK is the term after a child's

fifth birthday,   but it is common practice in England and Wales to admit children to reception class at the

beginning of the year in which they become 5,   which means that most children start school at the age of

4. The latest government figures indicate that around 80 percent of children enter school before their fifth

birthday.

     By comparison,   children in France,   Portugal,   Belgium start school at 6,   while the school starting

age in many Scandinavian countries is 7. This is the starting age in Finland,   where students recently beat

those from 39 other countries to come out tops in maths,   science and reading.

1. When her son is going to enter primary school,   the writer feels very ________.

A. excited  

B. worried  

C. surprised  

D. puzzled

2. In the UK,   it is stated in the law that children should start school at the age of ________.

A. 4  

B. 5  

C. 6  

D. 7

3. Which of the following is probably the best title of the passage?

A. Do our children start school too young?

B. Students starting school too young may cause problems

C. Young students may lead to failure

D. The age of starting school in some countries

4. What worries the writer is that her child ________.

A. can't even look after himself

B. can't dress himself

C. has some childish thoughts

D. has little ability in writing and reading

简述抓斗卸船机的工作原理。