对成年病人进行心肺复苏，心脏按压与人工呼吸必须交替进行的比例是（）。

The effect of the baby boom on the schools helped to make possible a shift in thinking about the role of public education in the 1920’s. In the 1920’s, but especially (1) the Depression of the 1930’s, the United States experienced a (2) birth rate. Then with the prosperity (3) on by the Second World War and the economic boom that followed it, young people married and (4) households earlier and began to (5) larger families than had their (6) during the Depression. Birth rates rose to 102 per thousand in 1946, 106.2 in 1950, and 118 in 1955. (7) economics was probably the most important (8) , it is not the only explanation for the baby boom. The increased value placed (9) the idea of the family also helps to (10) this rise in birth rates. The baby boomers began streaming (11) the first grade by the mid-1940’s and became a (12) by 1950. The public school system suddenly found itself (13) The wartime economy meant that few new schools were buih between 1940 and 1945. (14) , large numbers of teachers left their profession during that period for better-paying jobs elsewhere.

(15) , in the 1950’s, the baby boom hit an antiquated and inadequate school system. Consequently, the custodial rhetoric of the 1930’s no longer made (16) ; keeping youths ages sixteen and older out of the labor market by keeping them in school could no longer be a high (17) for an institution unable to find space and staff to teach younger children. With the baby boom, the focus of educators (18) turned toward the lower grades and back to basic academic skills and (19) . The system no longer had much (20) in offering nontraditional, new, and extra services to older youths.

19().

A. conference

B. symposium

C. seminar

D. discipline

《二十世纪中国的崛起》指出：“一个民族的觉醒，通常要有两个条件：第一，这个民族……被逼到生死存亡的关头，旧格局再也无法继续保持下去。第二，还要……能看到出路，……深信只要奋起救亡，勇于变革，就可以改变目前的艰难处境。”下列能够反映20世纪中国面临着两种形势的史实是

A．《马关条约》和公车上书

B．瓜分狂潮和义和团运动

C．《辛丑条约》和戊戌变法

D．《辛丑条约》和辛亥革命

以下工程实例中，属于刚度问题的是（）

A．起重钢索被重物拉断

B．车床主轴变形过大

C．齿轮轮齿被破坏

D．千斤顶螺杆因压力过大而变弯

阅读理解

     It's not easy being a teenager(13至19岁青少年)-nor is it easy being the parent of a teenager. You

can make your child feel angry, hurt, or misunderstood by what you say without realizing it yourself. It is

important to give your child the space he needs to grow while gently letting him know that you you'll still

be there for him when he needs you.

     Expect a lot from your child, just not everything.Except for health and safety problems, such as drug

use or careless driving; consider everything else open to discussion. If your child is unwilling to discuss

something, don't insist he tell you what's on his mind. The more you insist, the more likely that he'll clarn

up. Instead , let him attempt to solve(解决)things by himself. At the same time, remind him that you're

always there for him should he seek advice or help. Show respect for your teenager's privacy (隐私).

Never read him his mail or listen in on personal conversations.

     Teach your teenager that the family phone is for the whole family. If your child talks on the family's

telephone for too long, tell him he can talk for15 minutes, but then he must stay off the phone for at least

an equal period of time. This not only frees up the line so that other family members can make and

receive calls, but teaches your teenager moderation(节制). Or if you are open to the idea, allow your

teenager his own phone that he pays for with his own pocket money or a part -time job

1. The main purpose of the text is to tell parents      .

A. how to get along with a teenager    

B. how to respect a teenager

C. how to help a teenager grow up      

D. how to understand a teenager

2. What does the phrase "clam up" in Paragraph 2 probably mean?

A. refuse to talk  

B. show respect    

C.become excited      

D. seek help

3.The last paragraph is about how to teach a teenager

A. to answer the phone quickly      

B. to pay for his own telephone

C. to share the phone quickly        

D. to use the phone in a sensible way

4. What should parents do in raising a teenager according to the text?

A. Nor allow him to learn driving or take drugs  

B. Give him advice only when necessary

C. Let him have his own telephone            

D. Not talk about personal things with him

乳牙列存在着生理间隙，其中灵长间隙位于（）。

A.上颌的C与D之间

B.下颌的B与C之间

C.上颌的B与C之间

D.下颌的D与E之间

E.上颌的D与E之间