Exercise 4. Summarize your knowledge of Past Simple or Past Continuous. Choose the correct tense.

1. Keppler was inventing/invented the form of the refracting telescope.

2. British-Hungarian scientist Dennis Gabor was developing/developed the theory of holography while he was working/worked to improve the resolution of an electron microscope.

3. Alexander Graham Bell was patenting/patented an optical telephone system, which he called the Photophone, in 1880.

4. When did/was it become/becoming possible to produce holograms of high-speed events?

5. Dr. Stephen A. Benton was inventing/invented white-light transmission holography while he was researching/researched holographic television at Polaroid Research laboratories.

6. Sir Isaac Newton, the great scientist and thinker was discovering/discovered some of the fundamental laws of mechanics.

7. The union of electromagnetic theory with optics was beginning/began when Maxwell was finding/found that his equations for the electromagnetic field (1873) described waves travelling at the velocity of light.

8. From 1609 till 1610 Galileo Galilei was learning/learned of the invention of the telescope by Hans Lippershey.

9. Bernhard Schmidt was inventing/invented a third type of telescope.

Exercise 5.

a) Choose the correct modal verb.

Можно передать / (must, may, can) be transferred

Нельзя собрать / (must not, cannot, may not) be collected

Нужно придать параллельность / (must, may, can) be collimated

Нельзя обеспечить / (must, can, cannot) be provided

Можно возобновить / (must, can, cannot;) be resumed

Нужно получить / (must, can, cannot) be obtained

b) Translate from English into Russian, paying attention to modal verbs.

1. The diode radiation can be collected by a simple lens. 2. Illumination of a semiconductor may be followed by various consequences; electron conductivity, “intrinsic” photoconductivity, impurity or defect photoconduction. 3. A conductor and an insulator must be distinguished by their extreme values of electrical conductivity.