机械锯轨作业程序是什么？

以下哪项是经皮穿刺气管造口术的后期并发症（）

A.气道狭窄

B.气胸

C.空气栓塞

D.皮下气肿

E.出血

保密工作的原则是什么？

进口旧机电产品的收货人或其代理人，在进口旧机电产品到货( )日前，向备案机构申请备案。

A．30

B．60

C．90

D．180

阅读表达。

阅读下面短文回答问题(注意题后的字数要求)。

     In the United States,train transportation is unpopular compared with cars and airplanes. Most people

like traveling by car or by air.

     Officials of the United States Department of Transportation made a study in 2001. The study is about

how many miles Americans traveled by different means of transportation. They only studied trips longer

than 50 miles. The study showed that fifty-six percent of all miles were traveled in personal vehicle.

Forty-one percent were traveled in an airplane. Two percent were traveled in a bus. And less than one

percent of miles were traveled in a train.

     Amtrak is the national provider of train transportation in the United States. In the past ten years,the

number of its passengers has increased by eighteen percent. Although the number of passengers has

increased,it is still very small now. In countries such as France,Germany,or Japan,more people use trains.

     There are several reasons why many people __________________________.

     Firstly,Americans love to drive their own cars. On highways,cars can travel as fast as trains. These

highways connect all major cities in America. Secondly,many travelers like to be independent. When they

use their own cars they can decide when to travel. Thirdly,many buses travel between major cities. Bus

travel is less costly than train travel.

     In a huge country like the United States,cities are far away from each other. In some cases,travel

from one city to another by train may take more than a day. Airplanes can carry passengers over long

distances much faster. People who do not want to spend long time traveling by train decide to fly. For

these people saving time is the most important thing.

1. What is the best title of the passage? (Please answer within 10 words. )

2. Which sentence in the passage can be replaced by the following one?

It's convenient for people to decide the start-off time when they travel in their own cars. 

3. Please fill in the blank in the fourth paragraph with proper words or phrases to complete

    the sentence. ( Please answer within 10 words. )

4. What means of transportation do you like best when traveling,trains,cars,or planes? Why?

    (Please answer within 30 words)

5. Translate the underlined sentences in the last paragraph into Chinese. 

家庭离散对学前儿童成长的影响包括：对身体发育的影响、（）、对个性形成的影响、（）、对智力发展和学习成绩的影响。