17. There is… little white cloud in… sky.

18. We have. large room.

19. There is… big sofa in… room and… little lamp on… wall over… sofa.

20. I like to sit on… sofa and read… good book.

Answer the questions.

1. What is matter?

2. What does matter occupy?

3. Where does matter exist?

4. What are things in the physical world made up of?

5. What states does matter exist in?

6. What can matter undergo?

7. How many kinds of properties are there?

8. Are chemical properties permanent?

9. What may the various changes be?

10. Is it easy to reverse a physical change?

Make the sentences of your own using the new words (10 sentences).

Find the definite and indefinite articles in the text.

Find one word, which is a little bit different in meaning from others (найдите одно слово, которое немного отличается от других по смыслу):

1) a) nothing; b) anything; c) everything;

2) a) sense; b) feeling; c) gas;

3) a) ring; b) odour; c) taste;

4) a) colour; b) green; c) table;

5) a) feet; b) arms; c) molecule.

The components of the skeletal system are derived from mesenchy-mal elements that arise from mesoderm and neural crest. Mesenchy-mal cells differentiate into fibroblasts, chondroblasts, and osteoblasts, which produce connective tissue, cartilage, and bone tissue, respectively. Bone organs either develop directly in mesenchymal connective tissue (intramembranous ossification) or from preformed cartilage models (endochondral ossification). In general, the skeletal muscles differentiate from paraxial mesoderm. The splanch nic mesoderm gives rise to cardiac and smooth muscle.

The integument consists of the epidermis and its derivatives (glands, hairs, nails), and the underlying dermis. The epider mis is derived from ectoderm, whereas the dermis is formed from mesenchyme. Melanocytes, which may occur in both layers, originate from neural crest.

The skeletal system develops from paraxial mesoderm, which forms a column of tissue blocks, called the somites, on either side of the neural tube. Each somite becomes differentiated into a ventromedial part, the sclerotome, and a dorsolateral part, the dermomyotome. By the end of the fourth week, the sclerotome cells form embryonic connective tissue, known as mesenchyme. Mesenchyme cells migrate and differentiate to form fibroblasts, chondroblasts, or osteoblasts.

Bone organs are formed by two methods.

Flat bones are formed by a process known as intramembinous ossification, in which bones develop directly within mesenchyme.

Long bones are formed by a process known as endochondral ossification, in which mesenchymal cells give rise hyaline cartilage models that subsequently become ossified.

Skull formation. The neurocranium provides protection around the brain, and the viscerocranium forms the skeleton the face.

Neurocranium is divided into two portions:

The membranous neurocranium consists of flat bones that surround the brain as a vault. The bones appose one another at sutures and fon-tanelles, which allow overlap of bones during birth and remain membranous until adulthood. Palpation of the anterior fontanelle, where the two parietal and frontal bones meet, provides information about the progress of ossification and intracranial pressure.