Выберите правильный вариант ответа.
1. My cousin ... speak English well. I am sure she ... to help you with the translation.
can, will be able
is able, can
was able to, could
2. ... I use your pen? - Sorry, but I ... it at the moment.
Would, need
Could, need
Need, would use
3. He ... have gone hiking because he is ill. He ... be sleeping now, that`s why he hasn`t answered your call.
may, could
must, can`t
can`t, must
4. You ... go for a walk with your friends. Put on your warm sweater, it ... get colder.
have to, must
may, may
might, must
5. You ... take the dog for a walk every morning. If you keep a pet, you ... to look after it.
ought, must
must, should
should, ought
6. You ... to do the task in written form. But you ... hand it in tomorrow, you ... do it later.
are, needn`t, may
have, should, must
were, may, have
7. We ... to wear school uniform in class. However, we ... wear casual clothes during out-of-class activities.
ought, need
have, may
need, mustn`t
8. The readers ... speak loudly at the library. They ... use Wi-Fi free.
may not, can
must, may not
should, needn`t
9. ... I bring my own skates to the skating rink? - No, you ... . We`ll provide you with the sports equipment.
Can, have to
Must, needn`t
Need, are to
10. The conference ... to start at 10. You ... be late.
has, needn`t
must, are
is, mustn`t
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:
2. he said that he was not very well.
3. they said that they were going to get married the next month.
4. margaret said that she had had a baby.
5. i said that i did not know what fred was doing.
6. i said that i had seen helen at a party in june and she had seemed fine.
7. i said that i had not seen diane recently.
8. i said that i was not enjoying my job very much.
9. i said that you could come and stay at my flat if you were ever in london.
10. i said that my car nad been stolen a few weeks ago.
11. i said that i wanted to go on holidays but i could not afford it.
12. i said that i would tell anna id i had seen you.
просто заменяешь время на более прошлое в косвенной части:
past perfect
present simple
и т.д.