۰۲۱۶۶۴۰۳۳۰۲

جستجوی پیشرفته
درخواست کتاب
کتابهای 65 درصد کتابهای 60 درصد Package

: جمع سفارش 0

مشاهده سبد و پرداخت

درک مطلب مرداد 99 - EPT

Through a series of experiments, a scientist has obtained an understanding of the social structure of ant societies. The ants are the only creatures other than man to have given up hunting and collecting for a completely agricultural way of life. In their underground nests they cultivate gardens on soils made from finelychopped leaves. This is a complex operation requiring considerable division of labor. The workers of this type of ant can be divided into four groups according to size. Each of the groups performs a particular set of jobs. The making and taking care of the gardens and the nursing of the young ants are done by the smallest workers. Slightly larger workers are responsible for cutting leaves to make them suitable for use in the gardens and for cleaning the nest. A third group of still larger ants do the construction work and collect fresh leaves from outside the nest. The largest are the soldier ants, responsible for defending thenest. To find out how good the various size groups are at different tasks, the scientist measured the amount of work done by the ants against the amount of energy they used. He examined first the gathering and carrying of leaves. He selected one of the size groups, and then measured how efficiently these ants could find leaves and run back to the nest. Then he repeated the experiment for each of the other size groups. In this way he could see whether any group could do the job more efficiently than the group normally undertaking it. The intermediate-sized ants that normally perform this task proved to be the most efficient for their energy costs, but when the scientist examined the whole set of jobs performed by each group of ants, it appeared that some sizes of worker ants were not ideally suited to the particular jobs they performed.
1. Those children have special educational needs and ……………. a lot of attention.
2. This course aims to smooth the ………………. between education and employment.
3. Then network has enabled young ……………. to gain experience by working with qualified individuals.
4. Many complained ……………. about the lack of help she had received.
5. The new project will hopefully ……………. the effects of car pollution.
6. The flashing lights ……………... dangerous roads ahead.
7. Some newspapers rely on ……………... layout to attract more readers.

Video(Free)

  
No records to display.

محصولات مرتبط