Find all –ing forms in the text and define them. Translate the text in a written form.Diffusion is a process resulting from random motion of molecules by which there is a net flow of matter from a region of high concentration to a region of low concentration. A familiar example is the perfume of a flower that quickly permeates the still air of a room. Heat conduction in fluids involves thermal energy transported, or diffused, from higher to lower temperature. Operation of a nuclear reactor involves the diffusion of neutrons through a medium that causes frequent scattering but only rare absorption of neutrons. It is found that the rate of flow of the diffusing substance is proportional to the concentration gradient. If j is the amount of substance passing through a reference surface of unit area per unit time, if the coordinate x is perpendicular to this reference area, if c is the concentration of the substance, and if the constant of proportionality is D, then j = -D(dc/dx); dc/dx is the rate of change of concentration in the direction x, and the minus sign indicates the flow is from higher to lower concentration. D is called the diffusivity and governs the rate of diffusion.
23. Speak on the problem described in the text “BROWNIAN MOTION”. Make use of the following prompts: a) The main idea of the text is … The text runs (is) about … b) At first the author describes (defines, analyzes, determines, considers, regards, states that, etc)… c) Then the author passes on (to) (turns to) the description (analysis, definition, determination, consideration, etc) of …. It is pointed out (indicated, showed, admitted, etc) that … d) At the end of the text the author draws the following conclusion … The author concludes by stating (pointing out, stressing, underlining, emphasizing, etc) that … e) In my opinion (to my mind, I think (suppose, believe, etc) that …
24. Watch the films and give short summaries of them in a written form. What /new/information can you learn from them? Use expressions from Exercise 23. 25.
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