III. Put questions to the words given in bold type.

1. For the basic principles and equations of reflection to be derived we assume simple geometric relations between incident and reflected light rays. 2. Light was assumed to leave a source as an indefinite number of particles traveling in straight lines. 3. We observe rays of light from the same point source to be nonparallel to each other. 4. The path to be followed by any one of these imaginary particles is called a ray of light. 5. The ray to strike the mirror is called the incident ray. 6. The light to be reflected from a polished silver plate is an example of regular reflection.

IV. Answer the questions using the verb in brackets.

Model: Does this value change? (expect) → It is expected to change.

1. Does this metal become glowing at 300˚C? (expect) 2. Is the luminous intensity of a firefly measurable? (know) 3. Does platinum become glowing at this temperature? (assume) 4. Does this substance emit visible light? (see) 5. Is light from a fluorescent lamp incandescent? (doubt) 6. Are the two surfaces at equal distance from the point source? (find)

V. Find the predicate in sentences. Determine the function of the Infinitive in sentences and translate them.

1. The predicted precision was found to be difficult to obtain in practice. 2. Five or six orbit elements are known to be determinable. 3. Another important element in the filter technique to be treated in the equations is the parameter of observability. 4. The purpose of the experiment is to provide evidence of diffraction of light. 5. We are to provide all necessary equipment for the experiment to be carried out successfully. 6. This is the type of procedure to be followed to obtain accurate results. 7. The results presented here are supposed to indicate the type of procedure to obtain exact measurements. 8. To overcome this problem we return to the results listed in Table 2 where the initial weights are given. 9. To come to an approximate solution these values are assumed to be zero. 10. The present paper will present an attempt to apply a form of the Kalman filter to such systems to determine both the state estimation and the time delay.

Complex Object with the Infinitive

I. Translate the following sentences form English into Russian.

1. We know heat to have been a difficult problem to solve. 2. Do you know Galileo to have constructed the first air-expansion thermometer? 3. Aristotle assumed hot and cold to be connected with wet and dry. 4. One knows heat to have been of great importance for the development of industry. 5. The first investigator of heat found different substances to be heated to different degrees by the same amount of coal. 6. We know 19-th century physics to be great achievement of human mind.

II. Answer the question using the verb in brackets.

Model 1: Does this value change? (expect) – We expect it to change.

1. Do your friends know physics well? (expect). 2. Do they make physics experiments? (know). 3. Do they take interest in their future speciality? (believe). 4. Will the y take exams in physics? (suppose). 5. Will they get good marks in physics? (believe). 6. Will they become investigators soon? (doubt).

Model 2: Have they considered the problem yet? (believe). – We believe them to have considered it.

1. Has he made necessary measurements yet? (expect). 2. Have they checked the results yet? (believe). 3. have they accounted for this effect? (expect). 4. Has this value changed? (assume). 5. Has the platinum plate reached a sufficiently high temperature? (believe). Has he found an answer to this problem? (doubt).