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Reading comprehension -TOEFL- Lesson 89 (Đọc hiểu -TOEFL- Bài 89)

Đọc đoạn văn sau và trả lời các câu hỏi:

The texture of the soil depends on the relative amounts of different sized particles that combine to make up the soil. These particles can be as small as clay. A typical clay soil is composed of approximately 60 percent actual clay, 20 percent silt, and 20 percent sand. The 5 particles in a clay soil are so fine that it tends to be compact and interferes with the oxygen supply for plant roots. Water has trouble entering this impervious soil, and runoff is very common during rainfalls. A typical light sandy soil is composed of approximately 70 percent sand, 20 percent silt, and 10 percent clay. The particles 10 in a sandy soil are comparatively large, permitting water to enter the soil and to pass through it so quickly that it often carries nutrients with it and dries out very rapidly. The texture of sandy soils is generally very difficult to modify because huge amounts of organic material must be added. A typical loam soil is composed 15 of approximately 40 percent sand, 40 percent silt, and 20 percent clay, making it an ideal garden soil. It is easily worked and retains water and nutrients, which are slowly absorbed by plant roots.

A typical adobe soil is a clay soil present in hot, dry areas of the 20 country and often very hard and cracked. It has all the disadvantages of a heavy clay soil and, being much drier, is more difficult to correct.

1. What is the author's main purpose in the passage ?




2. According to the passage, the texture of sandy soil can be improved by mixing in




3. It can be inferred from the passage that the most distinguishing characteristic of adobe soil is





Grammar Easy Grammar Medium Grammar - Difficult
1->25 26->49 50->75 76->99 100->125 126->164
Ôn Tập Ngữ Pháp Phần 1 Ôn Tập Ngữ Pháp Phần 2