Аудиторная работа

ХЗУ. Проверка домашнего задания.

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ХV. Расположите зопросы в таком порядке, чтобы они могли служить планом к тексту А, и ответьте на них.

1. What methods of weed, control do you know?

2. What does the extoJ; of yield reduction vary with?

3. Why are woeds objectionable?

4. Can crop planus be weeds?

5. What do weeds compete with crop plante for?

ХVI. Укажите, какие из приведенных ниже слов могут сочетаться со словом production:

l) green, grain, grass, ground;

2) deficient, sufficient, efficient;

3) property, properly, proper;

4) valuable, vegetable, availablo, variable;

5) to increase, to include, to improve, to influence.

ХVII. Читая текст, догадайтесь о значении пропущенных слов и скажите, в каких случаях сорчякц бывают полезным (по-русски).

WEEDS ARE NOT ALWAYS HARRFUL

Although ... caused by weeds may be great, there aro certain benefits man can obtain from weeds. When the ... is not occupied by any crop, growth of weeds reducos soil and nutrient losses by erosion and leaching. Weeds also organic matter of the soil. They also provide ... for ani­mals and birds (птицы ). Good pasturage and hay being un­available, the more palatable ( вкусный ) weeds can be used to provide ... for livestock, The growth of weeds la effec­tive in catching and holding snow, thus providing ... to winter seodings. Some weeds are valuable for medicinal aud others for human consumption. A few of them are also used for ornamental (декоративный ) purposes.

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ХVIII. Протайте текст В, не пользуясь словарем. Дайте оценку биологического яетбда борьбы с соркякаки, укаките его преимущества и недостатки.

Text В BIOLOGICAL WEED CONTROL

Weeds have always' been a very important problem for agri­cultural specialists. Rapid spread of weeds in crop plants shews that the existing cultural and cheaical methods do net provide proper protection of farm crops. In addition, the latter method is not elways safe enough both for plants and people.

The biological control of crop weeds is now receiving ' much attention (внимание ) • Though it is known that this method is possible only in a limited number of situations,' that is, with certain insects and on certain weed species, it is rather attractive (приачехательный ) because where it does wort it is economical and environmentally-safe.

Useful insects have been used against some 86 weed speciss. As expected, some of the insect3 have been more successful then

others in becoming established (приняться )• Most of those that have been established appear to be highly beneficial.

Weed-feeding insects'were used on troublesome weeds in the state of Kontana as far back as 1948. However in­tensive studies of most of the insects were not conducted then. Ilho systematic studies of biological weed control method were started only in 1976.

One ehould know that the biological control of weeds

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in a very slow method, often requiring from 5 tc 10 years before the results can be seen.

Though this control method has certain limitations it is sure to become an important means of controlling crop weeds. By combining biological, chemical and other control methods with improved cultural practices, one will be able to effectively reduce the populations of many -: troublesome weeds.

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