B) Read the text and check

SMART MATERIALS Smart – or shape memory – materials are an invention that has changed the world of engineering. There are two types: metal alloys and plastic polymers. The metal alloys were made first and they are usually an expensive mixture of titanium and nickel. Shape memory materials are called ‘smart’ because they react to changes in their environment, for example: - plastics that return to their original shape when the temperature changes. One use is in surgery where plastic threads ‘remember’ the shape of a knot, react to the patient’s body temperature and make themselves into stitches; - metal alloys that have a ‘memory’ and can return to their original shape. They are used in medical implants that are compressed so they can be put inside the patient’s body through a small cut. The implant then expands back to its original shape. More everyday uses are for flexible spectacle frames and teeth braces; - solids that darken in sunlight, like the lenses in some sunglasses; - liquid crystals that change shape and colour. These have been used in climbing ropes that change colour if there is too much strain and weight on them. The future of these materials and their possible uses is limited only by human imagination. One clever idea is that if cars were made of smart metal, a minor accident could be repaired by leaving the car in the sun! * (the text is from: “Engineering” Workshop by Lindsey White, OUP; Unit 6, pg.7, ex.2)

3. Find in the text:

- …появились первыми…

- …дорогостоящая (смесь)…

- …изначальная форма…

- …температура человеческого тела…

- …помещать внутрь…

- …небольшой надрез…

- …возможные способы использования…

- …человеческое воображение…

- …незначительное повреждение…

Read the text again and choose the correct answers for questions (1–4) below.

1.	Smart materials change when
	a	the weather changes.
	b	something affects them.
	c	the light is switched on.
2.	Plastic threads are used for
	a	sewing.
	b	stitching.
	c	knitting.
3.	Medical implants made from shape memory alloys are good because
	a	they save lives.
	b	they change colour.
	c	they are easy to put in.
4.	Climbing ropes with liquid crystals change colour to
	a	warn you.
	b	amuse you.
	c	make you heavy.