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Complete the sentences using the Past Perfect tense of the verbs below.




Example: to learn the poem I went to bed after I had learnt the poem.

(to have dinner, to do homework, to come, to read the book, to clean the room, to go shopping, to return from Australia, to finish work)

I went to see my friend after...

I watched TV after...

They went home after...

He phoned me after...

She went to dance after...

We wrote a composition after...

They rebuilt the house after...

We went for a walk after...

Unit 9

Topic: Elements and compounds

Grammar: Modal Verbs

Elements and Compounds

More than 100 chemical elementssubstances that cannot be decomposed or broken into more elementary substances by ordinary chemical meansare known to exist in the universe. Russian chemist Dmitry Ivanovich Mendeleyev and German physicist Julius Lothar Meyer independently developed the periodic law of the chemical elements at about the same time in the late 19th century. Both discovered that arranging the elements in order of increasing atomic mass produced a table of chemical properties and reactivity patterns that were regularly repeated. This phenomenonknown as the periodic lawis most often represented in the periodic table of the elements.

Elements

Hydrogen, oxygen, chlorine, sodium, and iron are examples of elements. Elements cannot be resolved into simpler substances by ordinary heat, light, electricity, or attack by other substances. It requires either special equipment, such as a particle accelerator, or temperatures like those in the interior of the sun. Ninety elements are known to occur in nature, and 22 more have been made artificially. Out of this limited number of elements, all the millions of known substances are made. Abbreviating the names of the elements is often convenient. For each element, a symbol has been chosen that consists of one or two letters. The symbols are derived from the names of the elements; for example, H stands for hydrogen. The abbreviations are not always derived from the English names, however. The symbol Fe for iron comes from the Latin ferrum, and W for tungsten comes from the German wolfram.

Compounds

Salt, water, iron rust, and rubber are examples of compounds. A compound is made up of elements, but it looks and behaves quite differently, as a rule, from any of its component elements. Iron rust, for example, does not look and feel like its components: oxygen gas and iron metal. This individuality of properties, as well as other qualities, distinguishes a compound from a simple mixture of the elements it contains. Another important characteristic of a compound is that a compound has a definite, invariable composition, always containing the same elements in the same proportions by weight; this is the law of definite proportions.

Vocabulary

Substance

universe

physicist

atomic mass

heat

Equipment

occur

iron rust

rubber

contain

composition

weight

Ask three questions to each of the passages. Let your group mates answer them.

Retell the text.

3. Give brief characteristics of the elements that you have met in the text.

Your description should include: atomic number, atomic mass, group, period, row, chemical and physical properties.

 

Modal Verbs

- (), . : can - could, may - might ( will - would, shall - should), , , .

: to have, to be (=must), to be able (=can), to be allowed, to be permitted (=may).

 

Can ( to be able to)

Can
Could
-. , , ,
1. Can .
  • My friend can write compisitions well
  • Can he persuade us? ?
  • Those workers cant speak English - ( ).
2. Could , .
  • Mary could play tennis well .
can/could to be able to. can/could (I am able, she was able ..), , can/could (She has been able, Peter will be able ..)
  • My friends will be able to translate this text .
can , can not cannot.

Should

.
1. .
  • Mary should be more polite .
2. .
  • What should I do now? ?
, should.

May/Might ( to be allowed to)

. , , ..
1. .
  • John may smoke here .
2. .
  • My neighbour may know about that accident , , .
  • It may snow today , , .
3. Might , .
  • My sisters might call tonight , , .
4. Might ( ). might , .
  • If Tom were here, he might show the magazine , .
may , might, to be allowed. .
  • John was allowed to smoke there .
  • Peter will be allowed to speak English .

Must ( to have to)

. , must , . must , , .
1. , , ( ).
  • You must be here at 5 o'clock 5 .
  • She mustn't stay here .
2. .
  • Mary must be at the station now , (), .
must , have to.
  • My friend had to bring the newspaper .

Ought

. ought , , .
1. .
  • You ought to help your aunt ( , ) .
  • Kate ought to be more polite ( , ) .
Ought should.
ought to.

Need

-. , . .
1. - (need ). Need John invite her? ? 2. (need ).
  • I dont need her help any longer .
.

Exercises

 
Ex. 1 Choose must, ought to, should, have to. Write the negative particle not where is necessary.
1. If you want to be fit, you.. eat cake. 1. should 3. ought 5. have 7. will 2. shouldn't 4. to 6. must 8. don't 2. The bus we took didn't go up the hill and we.. walk. 1. must 3. to 5. didn't 7. had 2. shouldn't 4. don't 6. oughtn't 8. have 3. Every child.. know traffic rules. 1. mustn't 3. ought 5. have 7. has 2. shouldn't 4. to 6. oughtn't 8. doesn't 4. My parents are going out to a party tomorrow and I.. stay with my younger brother. 1. 'll 3. have 5. shouldn't 2. must 4. oughtn't 6. to 5. It's dark outside, it.. be about 7 now. 1. has 3. to 5. ought 2. should 4. not 6. must 6. You.. eat so many sweets because they contain a lot of calories. 1. must 3. ought 5. won't 7. to 2. should 4. don't 6. shouldn't 8. have 7. If you want to be fit, you.. walk a lot. 1. shouldn't 3. ought 5. has 7. mustn't 2. oughtn't 4. to 6. don't have 8. When he was at the university he.. work to pay for his education. 1. had 3. ought 5. has 2. should 4. must 6. to 9. You are impolite. You.. speak to your mother like this. 1. to 3. have 5. must 2. should 4. ought not 6. ought 10. Mother... leave early on Mondays so he... make his breakfast himself. 1. shouldn't 3. has to 5. doesn't 2. oughtn't to 4. have to 6. must
Ex. 2
 
Choose can must, ought to, should and their equivalents. Write the negative particle not where is necessary.
1. Sally's husband... play football, tennis and other games but he... cook or iron. 1. can 3. may 5. must 2. can't 4. not 6. should 2. Ann,... I ask you a question? - You certainly.... 1. can 3. may 5. must 2. can't 4. not 6. should 3. I wonder if we... take off our shoes here. 1. can 2. can't 3. may 4. not 5. must 4. You... always observe traffic rules on the road. 1. can 3. may 5. must 2. can't 4. not 6. should 5. You... stay in town the whole summer or you... go to the seaside if you want. 1. can 3. may 5. must 2. can't 4. not 6. should 6. You...... take so much sugar in your tea. 1. can 3. must 5. have 7. are 9. able 2. may 4. ought 6. should 8. not 10. to 7. Dan,... I do anything for you? 1. can 3. may 5. must 7. have 9. to 2. can't 4. not 6. should 8. am 10. allowed 8. Mrs. Brown,... I go out for a moment? - No, you....... 1. can 3. may 5. must 7. ought to 9. do 2. can't 4. not 6. should 8. have to 9. He... return later. If he comes late, you... wait. 1. can 3. may 5. must 7. 'll have to 9. are allowed to 2. can't 4. not 6. should 8. are to 10. ought to 10. Mom,... we meet them at the airport? - No, you.... 1. can 3. may 5. must 7. do 9. have to 2. can't 4. not 6. should 8. needn't 10. might 11. I have a terrible headache. - I think you... see a doctor. 1. can 3. may 5. are allowed to 7. are able to 9. had to 2. can't 4. needn't 6. should 8. must 10. are to 12. The people are carrying umbrellas. It... be raining. 1. can 3. may 5. must 7. ought to 2. can't 4. not 6. should 8. has to 13. I know I... help my sister about the house. 1. can 3. may 5. am allowed to 2. can't 4. ought to 6. could 14. You... take all this tablets if you want to get well. 1. can 3. may 5. are able to 7. are to 2. can't 4. not 6. should 8. are allowed to 15. Schoolchildren... not wear a uniform now. 1. can 3. may 5. should 2. can't 4. must 6. ought to 16. Sally... be Mary's daughter. Mary is too young to be her mother. 1. can 3. may 5. must 7. ought to 9. has to 2. can't 4. not 6. should 8. needn't 10. is able to 17. Oh,... she be angry with me? I didn't say anything offensive. 1. can 3. may 5. must 7. ought to 9. is able 2. can't 4. not 6. should 8. has to 10. is allowed to 18. I'm afraid something is wrong. They... be back an hour ago. 1. can 3. may 5. must 7. are allowed to 9. were to 2. can't 4. not 6. were able to 8. are to 10. had to 19. In my childhood I... learn three foreign languages. 1. can 3. may 5. must 7. ought to 9. have to 2. can't 4. not 6. should 8. was to 10. was able to 20. - Max,... you help me with Math? - No, I.... I... read a whole chapter in Geography. 1. can 3. may 5. must 7. ought to 9. was to 2. can't 4. not 6. should 8. had to 10. am able to

Ex. 3

Translate into English.

1. . 2. . 3. , . 4. . 5. , . 6. , . 7. , . 8. . 9. , . 10. ? .

Ex. 4





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