Прочитайте текст и выполните задания.

Text 1

Electricity

Прочитайте текст и выполните задания.

1. Electricity is a flow of negative charges called electrons. These electric charges are measured in units called coulombs. Electricity is a very versatile form of energy that can be converted into many other forms of energy, including light and heat, direct current (DC), which flows in one direction only, and alternating current (AC), which changes direction 60 times per second.

2. An electric circuit is an unbroken conducting path from, and back to, a power supply. It has three main parts: the power supply, the conductor, and the load. The power is provided by a generator or battery, the conductor carries the current, and the load is an electric device such as a lamp.

3. Unlike current electricity, static electricity does not flow. It is created when an electrically neutral substance loses or gains electrons, making it, respectively, positively or negatively charged. You can create static electricity by rubbing a balloon on your clothing. Electrons will move from the clothing to the balloon, making the balloon negatively charged and the clothing positively charged. The resulting static electricity on each will attract small, light objects such as pieces of paper.

1. Определите, какое утверждение соответствует содержанию текста.

	There exist two different types of electricity.
	Electricity can be changed into various energy forms.
	An electric circuit exists in every type of electricity.
	People are able to create static and resulting electricity themselves.

2. Завершите утверждение согласно содержанию текста.
The kind of electricity which can be created at friction is called …

	resulting electricity
	alternative current
	direct current
	static electricity

3. Ответьте на вопрос:
What device is designated for the continuous flow of electric current?

		Electrical circuit allows electrons to flow through continuously without beginning or end.
		In an electric circuit the load can be an electric device such as a lamp.
		One can create static electricity by rubbing a balloon on one’s clothing.
		The power in an electric circuit is provided by a generator or battery.

4. Определите основную идею текста.

	It is a scientifically proved fact that electricity is a flow of negative charges called electrons.
	Electricity is a very changeable energy form being presented by different kinds.
	There exist different kinds of electricity, electrical properties of which being quite alike.
	Electricity is a versatile form of energy that can be converted into many other energy forms.

Text 2

Solid

Прочитайте текст и выполните задания.

1. Solid is one of the major states of matter. It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a gas does. The atoms in a solid are tightly bound to each other, either in a regular geometric lattice or irregularly one.

2. The branch of physics that deals with solids is called solid-state physics, and is the main branch of condensed matter physics (which also includes liquids). Materials science is primarily concerned with the physical and chemical properties of solids. Solid-state chemistry is especially concerned with the synthesis of novel materials, as well as the science of identification and chemical composition.

3. The forces between the atoms in a solid can take a variety of forms. For example, a crystal of sodium chloride (common salt) is made up of ionic sodium and chlorine, which are held together by ionic bonds. In diamond or silicon, the atoms share electrons and form covalent bonds. In metals, electrons are shared in metallic bonding. Some solids, particularly most organic compounds, are held together with van der Waals forces resulting from the polarization of the electronic charge cloud on each molecule. The dissimilarities between the types of a solid result from the differences between their bonding.

1. Определите, какое утверждение соответствует содержанию текста.

	A solid’s properties are quite different from those of a gas or a liquid due to its structure and the ability to resist.
	It has been an accepted fact that the quantity of atoms in a solid’s lattice is permanent.
	The existence of various solids can be explained by different types of their lattices.
	It is possible to change a solid’s state modifying its chemical bonds.

2. Завершите утверждение согласно содержанию текста.
A solid has a constant form …

	if only possessing covalent bonds
	depending on the type of its lattice
	as the atoms in it are tightly bound to each other
	that’s why it is difficult to identify its chemical composition

3. Ответьте на вопрос:
Why do there exist different types of solids?

	This happens due to certain amount of electrons in a solid.
	This is due to the type of a chemical bond a certain solid possesses.
	It is influenced by its structural rigidity and resistance to any changes.
	It depends on different types of lattices of solids.

4. Определите основную идею текста.

	A solid has its own distinctive characteristics which are studied by different branches of sciences.
	The text deals with similarities and differences among solids possessing different bonds.
	The text introduces the readers to description of various properties of solids, gases and liquids.
	Solids are quite difficult to be distorted due to their structural rigidity and resistance to changes of shape or volume.

Text 3

Light