все надо решить Раскройте скобки, поставив глагол в настоящее совершённое продолженное время (Present Perfect Continuous):
1.We (study) online since April 6.
2.Olga (work) here for five years.
3.How long (you/study) Spanish?
4.The kids (play) football since 6.00 PM.
5.Anna (wash) dishes for half an hour.
2. Вставьте в предложения нужную форму модального глагола have to:
1.I wake up early as my work starts at 8.00 AM.
2.Marina take the dog for a walk before she leaves.
3.It’s Sunday. We go to school.
4.I go to the dentist yesterday.
5. You take away the rubbish. I have done it.
3. Допишите «хвостики» к во Переведите предложения на английский язык:
1.Вы можете узнать об исчезающих видах растений и животных в Красной книге.
2.В субботу жители Белоруссии вместе с Президентом надели садовые рукавицы, взяли грабли, вёдра, большие пластиковые пакеты и отправились собирать мусор с улиц страны.
3.Заводы и электростанции выделяют токсичные выбросы в атмосферу.
4.Кислотный дождь отравляет деревья, растения, рыб, животных.
5.Это неправда. Катя выдумала всю эту историю.
6.Правительство уже несколько лет пытается уменьшить загрязнение окружающей среды.
7.Я не могу разобрать твой почерк.
8.В нашем дворе есть контейнеры, в которых мы оставляем мусор для вторичной переработки.
Plastics are non-metallic, synthetic, carbon-based materials. They can be moulded, shaped, or extruded into flexible sheets, films, or fibres. Plastics are synthetic polymers. Polymers consist of long-chain molecules made of large numbers of identical small molecules (monomers). The chemical nature of a plastic is defined by the monomer (repeating unit) that makes up the chain of the polymer. Polyethene is a polyolefin; its monomer unit is ethene (formerly called ethylene). Other categories are acrylics (such as polymethylmethacrylate), styrenes (such as polystyrene), vinys (such as polyvinyl chloride (PVC)), polyesters, polyurethanes, polyamides (such as nylons), polyethers, acetals, phenolics, cellulosics, and amino resins. The molecules can be either natural — like cellulose, wax, and natural rubber — or synthetic — in polyethene and nylon. In co-polymers, more than one monomer is used.The giant molecules of which polymers consist may be linear, branched, or cross-linked, depending on the plastic. Linear and branched molecules are thermoplastic (soften when heated), whereas cross-linked molecules are thermosetting (harden when heated).Most plastics are synthesized from organic chemicals or from natural gas or coal. Plastics are light-weight compared to metals and are good electrical insulators. The best insulators now are epoxy resins and teflon. Teflon or polytetrafluoroethene (PTFE) was first made in 1938 and was produced commercially in 1950.Plastics can be classified into several broad types.1. Thermoplastics soften on heating, then harden again when cooled. Thermoplastic molecules are also coiled and because of this they are flexible and easily stretched.Typical example of thermoplastics is polystyrene. Polystyrene resins are characterized by high resistance to chemical and mechanical stresses at low temperatures and by very low absorption of water. These properties make the polystyrenes especially suitable for radio-frequency insulation and for parts used at low temperatures in refrigerators and in airplanes. PET (polyethene terephthalate) is a transparent thermoplastic used for soft-drinks bottles. Thermoplastics are also viscoelastic, that is, they flow (creep) under stress. Examples are polythene, polystyrene andPVC.2. Thermosetting plastics (thermosets) do not soften when heated, and with strong heating they decompose. In most thermosets final cross-linking, which fixes the molecules, takes place after the plastic has already been formed.Thermosetting plastics have a higher density than thermoplastics. They are less flexible, more difficult to stretch, and are less subjected to creep. Examples of thermosetting plastics include urea-formaldehyde or polyurethane and epoxy resins, most polyesters, and phenolic polymers such as phenol-formaldehyde resin.3. Elastomers are similar to thermoplastics but have sufficient cross-linking between molecules to prevent stretching and creep.
Объяснение:
Ex.1
1.many birds fly south in winter.
2. Ken writing a book about the Aztec Indians. He`ll finish it soon.
3. Mandy usually sits with Sandra in history classes. But today Sandra is absent, so Mandy will sit with Beth.
4. We don't wear uniforms to school.
5. “Great John! I see you are working very hard today! "
6. My brother doesn't listen to pop music, but today he listens to Madonna.
7. I don't understand what you are saying. Please speak more clearly!
8. I support Greenpeace because I believe in their philosophy.
9. Our teachers giving us a test twice a month.
10. "What are you doing?" "I taste the soup to see if it has enough salt."
Ex.2
1.Be careful! You will hurt yourself with scissors.
2. Come quickly! Look, snow out!
3. I do not know the answer, so I am looking it up.
4. The buses leave from the depot at 9 o'clock every day.
5. When I grow up, I will become an astronaut.
6. If you keep on play with this knife, you will cut yourself.
7. I will wear my new dress to the party tonight!
8. Jane will visit us these days and we are having a wonderful time together!
9. Don't worry! The plane will take off in three hours. We have a lots of time!
10. Jenny will be back soon. You could wait for her if you like.
Ex.3
1.My father took me to my first football game ten years ago.
2. When I arrive home, Susan cries.
3. Luke and Tony have a fight over Sheila at the pub last night.
4. I wrote an email when a dog comes in.
5. When I was young, my mum walk me to school every morning. In the afternoon my grandmother picked me up because my mother had to work.
6. While I driving to work, it startted snowing.
Ex.4
1. My father will take us to the park tomorrow.
2. Mary is doing her homework for tomorrow.
3. We live at 17 Burrows Street.
4. All day yesterday they were preparing for the English test.
5 . My mother worked in a good store before she was married.
6. We clean the house every day.
7. “Don't worry John, I'll pick up my dry cleaning on my way home. "
8. I will go to China if I win a lot of money.
9. My brother goes to school every morning.
10. When she was crossing the road, she was hit by a motorcycle.
11. When she arrives, we will ask her about it.
12. I will visit her while I am in Athens.
13. Ten minutes ago he took out the trash.
14. Do you get a lot of gifts for your birthday?
15. I will help with the laundry if I have time.
Ex.5
1.c
2.b
3.b
4.c
5.c
6.c
7.a
8.c
Объяснение: