Рубрика:
17
11. Перепишите данные предложения, определите в них видовре-
менные формы глагола и укажите их инфинитив. Предложения пе-
реведите.
1. In 1712 St. Petersburg became the capital of Russia. 2. For citizens of
St. Petersburg the embankment of the Neva is one of the most beautiful
places in the world. 3. St. Petersburg got its name in 1703. 4. I shan’t go out
now as I have a lot of work to do. 5. They do their shopping every day.
12. Перепишите и переведите приводимые ниже предложения. По-
ставьте их в отрицательной форме. Задайте общий и специальный
вопрос к каждому предложению.
1. Tim does his morning exercises every day. (What?). 2. He always smokes
before lunch. (When?) 3. Mary’s mother taught her how to cook. (Whom?) 4.
Yesterday we spent a lot of money. (What?) 5. My sister will wear her new
dress. (When?) 6. We shall join them later. (Why?)
13. Прочтите и устно переведите текст. Перепишите и письменно
переведите 3-й абзац текста.
Basic Solid-State Principles
In a conductor, electric current flow is a movement of free electrons.
The outer or valence electrons of a good conductor are loosely bound to
the atom. At room temperature the thermal energy causes approximately
one electron to detach from each atom and become free to move and
result in a current flow when an electric potential is applied.
Insulators are materials in which outer electrons are tightly bound to the
atom and no electrons are free to move. Thus, no current can flow when
voltage is applied.
Between these two major categories is a class of materials called
semiconductors. As the name implies, a semiconductor is a material with
conductivity roughly midway between conductors and insulators. It is not
just a poor conductor; it has two important properties. First, its resistance
normally decreases with increase of temperature, while in conductors
resistance slightly increases with temperature. Second, the flow of current
in a semiconductor may be caused either by a flow of negative electrons or
by a movement of missing sites in the opposite direction. If an atom has
one outer electron missing, a loosely bound electron from a neighbouring
atom can jump into it, leaving behind a new vacant site; this, in turn, can
be filled by an electron from the third atom and so on. The impression is
as if the vacant site has moved. Such vacant sites are called “holes” and
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