Определите время и залог: 1)surgery is sometimes required to rebuild the bone that has been destroyed. 2)on examination you will be asked a lot of questions on your habits and be given thorough examination of your oral cavity. 3) surgical operations on teeth and the oral cavity have been known since ancient times. 4) periapical radiographs are always taken to check for a root fracture. 5) currently the light activated glass ionomer products are being used extensively as lines. 6) the dentist was brought all the sterilized instruments and the operation began. 7) that calcium hydroxide possesses a strong antibacterial capacity has already been recognized at the time of its introduction. 8) healing of periradicular inflammation may not take place until all bacteria have been eliminated from the root canal system. 9) the proteins of the fibrils and dentinal matrix are being metabolized largely by pyogenic organisms giving rise to poisonous end products swallowed by the patient. 10)a new ultrasound device has been designed to treat an infected tooth without causing any pain.

1) is  required (present simple passive);   has been destroyed (present perfect passive)2) will be asked  and be given (future simple passive) 3) have been known (present perfect passive) 4) are taken (present simple passive) 5) are being used (present progressive passive)6) was brought (past simple passive); began (past simple active) 7) possesses (present simple active); has already been recognized (present perfect passive)8) have been eliminated (present perfect passive) 9) are being metabolized (present progressive passive)10) has been designed (present perfect passive)

Ecological problems harmfully affect the environment. among the most actual problems are: ozone layer, acid rains, global warming, toxic air pollution, (лучше сказать не исчезновение, а вырубка лесов) deforestation, chemical pollution of groundwater, soil destruction in certain areas and  the extinction of plant and animal  species. the earth is home for millions of creatures, which  constitute the complicated wild world. nowadays people try to change habitat of animals  in order to  satisfy personal needs, to create farmlands and to build cities. digging the ground for coal mining and road building,  they pollute and destroy the habitat of wild world. it's known that  quarter of all plants are  endangered. there are diverse kinds of pollution: water pollution, air pollution, soil pollution and radioactive pollution. acid rain falls when  poisonous gases from nuclear power stations and exhaust fumes from vehicles mix with  oxygen and  the moisture of the air. these gases become the part of water cycle and can be spreaded by wind for a long time, untill it will fall as an acid rain, which damage creatures in lakes, rivers, forests and affects harmfully the  existence of plants. world temperature increase every year. this process is called the global warming. it's caused by congestion of gases and  water evaporation in the atmosphere. these gases form the layer, which reflect heat back to the earth. as the planet warms, polar ice starts melting. it can causes the increasing of sea level, and certain habitats will disappear under the water. ecological problems are boundless. nevertheless, it's possible to  avoid environmental catastrophes if people will deep their ecological  knowledge, and everyone will understand, that the beauty of nature is too delicate. government should take measures to protect the environment from pollution.

Nvironmental problems they cause great harm to the environment. among the most relevant is the ozone layer, acid rains, global warming, toxic pollution, deforestation, pollution of groundwater with chemicals, soil degradation and erosion in some areas, and the threat of representatives of flora and фауны.земля is home to a million creatures that make up the complex world of nature. in our days people try to change their environment to suit their needs - create agricultural land or to build cities. they pollute and destroy the environment wildlife, digging the earth for a coal or building roads. it is known that a quarter of all plants is endangered. there are different types of pollution: water, air, pollution of land and радиоактивное.кислотный rain falls when toxic gases from nuclear power stations and vehicle emissions are mixed with oxygen and moisture in the air. these gases become part of the water cycle, and can be a long time spread by the wind, before falling out by acid rain which kills life in lakes, rivers and forests and destroying the lives of растений.мировые temperature increases every year. this so-called global warming is caused by the accumulation of gases and evaporation of water in the atmosphere. these gases form a layer that reflects heat back to the earth. as the planet heats up, the polar ice will begin to melt. this can cause a rise in sea levels, and many of habitat will disappear under the водой.экологические problems have no borders. however, environmental disasters can be avoided if people would expand their environmental knowledge, and everyone will understand that the beauty of nature is very fragile. the government should take serious measures against pollution of the environment.