Предмет: Английский язык, автор: Аноним

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The track is one of the basic features of a railway. It is also called the permanent way. The fact is that in the early days of railroad building the workers first had to lay temporary tracks to transport the materials to the construction site.
And only after that they laid down the permanent tracks on the permanent way, as it was called. The permanent way consists of rails, ties and ballast.
The railroad track of today is quite different from that used in the early days of railways.
The first tracks had no ballast, the rails were made of wood and rested on heavy blocks of granite. Then the wooden rails were replaced by iron ones, and the granite blocks were replaced by wooden ties.
This kind of track, however, was not strong enough for heavy steam trains.
The discovery how to make cheap steel was of great importance to the railways for, when placed in the same track, steel rails had a life 15 (fifteen) times as long as iron rails.
The distance between the rails is called the gauge. The standard gauge in most countries is 1,435 ( one thousand four hundred thirty five ) mm while in Russia the railroads have a gauge of 1,524 (one thousand five hundred twenty four) mm. That gauge was finally adopted when the first main - line Moscow – St. Petersburg railway was under construction (1842 one thousand eight hundred forty two - 1851 one thousand eight hundred fifty one). Thus Russia was the world's first country where the uniform gauge was adopted for all railways. In America the gauge was unified only in 1886 (one thousand eight hundred eighty six) .
The place where the ends of the rails meet in the track is known as the rail joint.
The rail joint has always been the weakest part of the track for nearly all the rails wear out first at the ends.
Some railroads have two or more tracks.
In order to make the trains pass from one track to another the railroads have a switch which is a very important element of the track.
The rails differ greatly in weight according to the kind of traffic which they are to carry when placed in the track. The largest and heaviest rails are laid in the main-line tracks for it is these tracks which carry the largest volume of traffic.
The ties on most tracks were almost all of wood and in order to make them last longer they were treated with creosote. The ties are not laid upon the earth for the earth cannot support the track structure. They rest upon a bed of crushed rock, or gravel, which is called ballast. Ballast supports the track structure, holds the track in position and provides needed drainage.
The history of railways is more than one century and a half. During this period the track structure has been substantially improved. One of the greatest improvements was the elimination of rail joints. In order to reduce the number of joints the rails are welded into continuous lengths.These continuous or long welded rails have greater strength and provide a smoother running of trains at far greater speeds.
Another improvement which has made it possible to increase speeds on railways is the use of concrete sleepers. Thus in some countries , concrete sleepers have replaced wooden ones on heavily used main lines because of their advantages.
Concrete sleepers have a longer life and a far greater weight than those made of wood. The greater weight of concrete sleepers provides the greater stability of track.
It is this factor which has greatly contributed to increased speeds.
What elements does the permanent way consist of?
What is the origin of the term permanent way?
What is the difference between the modern railroad track and the track of the early days of railways?
What is the gauge and what gauge is used on the Russia railways ?
Why is the joint the weakest part of the track ?
What is the switch intended for?What does the weight of the rails laid in the track depend on? Why are the heaviest rails laid on the main- line tracks? How can we make wooden ties last longer? Are the ties laid upon the earth ? Why aren’t they ?

Ответы

Автор ответа: Englishman14
1
1)The permanent way consists of rails, ties and ballast.
2) Temporary track
3)The first tracks had no ballast, the rails were made of wood and rested on heavy blocks of granite
4)The distance between the rails is called the gauge. in Russia the railroads have a gauge of 1,524
5)The rail joint has always been the weakest part of the track for nearly all the rails wear out first at the ends.
6)In order to make the trains pass from one track to another the railroads have a switch which is a very important element of the track.
7)The largest and heaviest rails are laid in the main-line tracks for it is these tracks which carry the largest volume of traffic.
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Предмет: Английский язык, автор: yanegr123
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WHY DON’T BRITISH SCHOOLCHILDREN WANT TO EAT FRUIT AND VEGETABLES?

There are many problems that British schools are facing today. One of them is making sure that schoolchildren eat healthy food.

Gone are the days when children were thrilled with excitement at the thought of Christmas treats like oranges and tangerines or simple desserts like rice pudding. Nowadays any fruit and vegetables under the sun can be bought in supermarkets all the year round. There is only one problem with that — fruit and vegetables that are bought out of season have very little taste. On the contrary, sugar drinks like Coke and numerous varieties of flavoured crisps are full of flavour — and chemicals additives! Also, most British mums of today work full time and the last thing they want to do when they get home is cook. Supermarkets are here to «help» — pre-package and ready-made meals have filled their shelves.

As a result, many schoolchildren would rather go hungry than eat fruit or vegetables instead of the more familiar crisps, burgers and chips.

There’s nothing wrong with having a can of Coke every now and then but four cans a day is asking for trouble. Did you know that a can of Coke contains about eight teaspoons of sugar and artificial sweeteners? As a result, many modern kids suffer from such illnesses as diabetes, cancer and tooth decay. And, of course, there are more and more children who are extremely overweight.

In Britain, children can either choose to bring their own lunch or buy their lunch at school. Children from poorer families can have free school dinners but many of them don’t take them for various reasons.

Say if the following statements true or false.

1. Many years ago children couldn’t even dream about pineapples.

2. Nowadays you can buy pineapples when you wish.

3. In supermarkets fruit and vegetables are tasty and full of vitamins all the year round.

4. A lot of pre-package and ready-made meals contain chemical additives.

5. Many schoolchildren would rather eat some salad than stay hungry.

6. You should never have Coke. It’s harmful.

7. Coke contains a lot of unhealthy things.

8. Fast food and Coke can cause dangerous illnesses and overweight.

9. In Britain children can have lunch only at school.

Complete the sentences.

Tastiest, illnesses, tastier, chemicals, cooking, healthy

1. Children should have only ... without... .

2. Many years ago fruit and vegetables were ... than nowadays they are.

3. The ... meal is that one which you’ve done yourself just before serving.

4. An ad says: «You have no time for ...? Come to our supermarket — we’ll help you!»

5. Cola can cause many ... .

Answer the questions.

1. Why don’t children like fruit and vegetables nowadays?

2. Why do most mums prefer ready-made meals?

3. What is wrong with Cola?

4. What is the reason of different illnesses and overweight among children?
Предмет: Биология, автор: vladimirzverev03
1. Скрещивание особи с другой особью, имеющей гомозиготные рецессивные аллели гена, называется

рецессивным
анализирующим
доминантным
сцепленным с полом

2.Какая из характеристик не относится к модификационной изменчивости?

имеет индивидуальный характер
имеет групповой характер
характерна для всех особей вида
не передается из поколения в поколение

3. Эффект гетерозиса наблюдается при

скрещивании разных сортов растений и пород животных одного вида

близкородственном скрещивании (бык и корова, приходящиеся друг другу братом и сестрой)

скрещивании растений одного сорта и животных одной породы

межвидовой гибридизации


4. Определите, сколько возможных типов гамет образуется у особи с генотипом Ааbb

1
4
2
8
5. Определите вероятность рождения у темноволосых родителей-гетерозигот детей со светлыми волосами, если темный цвет доминирует над светлым

75%
25%
0%
100%
6. Утрата части хромосомы называется
полиплоидией
инверсией
дупликацией
делецией

7. Митоз при гаметогенезе происходит

в зоне созревания
в зоне роста
в зоне размножения
в зоне формирования

8. В результате митоза дочерние клетки имеют хромосомный набор

n
2 n или 4 n
2n
4n

9. Веретено деления формируется в

анафазе митоза
метафазе митоза
телофазе митоза
профазе митоза

10. Что такое трансляция?

«переписывание» информации с иРНК на ДНК
«перевод» информации с «языка» нуклеотидов на «язык» аминокислот
«переписывание» информации с ДНК на иРНК
редупликация ДНК

11. Выстраивание хромосом по экватору клетки происходит в

телофазе митоза
профазе митоза
метафазе митоза
анафазе митоза

12. Сколько аллелей разных генов отвечает за наследование цвета волос (темный и светлый), формы носа (прямой и с горбинкой) и цвета глаз (карий и голубой)?

9
1
6
3

13. Выберите несколько вариантов ответа

Отметьте особенности мейоза

a. поддерживает постоянство количества хромосом в поколениях
b. образуются 4 гаплоидные клетки
c. происходит в соматических клетках
d. участвует в образовании гамет животных
i. обеспечивает рост организма
f. лежит в основе регенерации органов

14. Выберите несколько вариантов ответа

Отметьте процессы, характерные для третьего этапа энергетического обмена в клетке

a. протекает в анаэробных условиях
b. протекает в митохондриях
c. образуется 2АТФ
d. образуется 36 АТФ
i. проходит в цитоплазме клетки
f. протекает в аэробных условиях

15. Установите соответствие


a. фрагментация (деление на части кольчатых червей)
b. спорообразование у грибов
c. спорообразование у растений
d. почкование дрожжей
i. образование гамет
f. почкование гидры
1. половое размножение
2. бесполое размножение