Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 35 to 42.

        Desertification is the degradation of once-productive land into unproductive or poorly productive land. Since the first great urban-agricultural centers in Mesopotamia nearly 6,000 years ago, human activity has had a destructive impact on soil quality, leading to gradual desertification in virtually every area of the world.

        It is a common misconception that desertification is caused by droughts. Although drought does make land more vulnerable, well-managed land can survive droughts and recover, even in arid regions. Another mistaken belief is that the process occurs only along the edges of deserts. In fact, it may take place in any arid or semiarid region, especially where poor land management is practised. Most vulnerable, however, are the transitional zones between deserts and arable land; wherever human activity leads to land abuse in these fragile marginal areas, soil destruction is inevitable.

        Agriculture and overgrazing are the two major sources of desertification. Large-scale farming requires extensive irrigation, which ultimately destroys lands by depleting its nutrients and leaching minerals into the topsoil. Grazing is especially destructive to land because, in addition to depleting cover vegetation, herds of grazing mammals also trample the fine organic particles of the topsoil, leading to soil compaction and erosion. It takes about 500 years for the earth to build up 3 centimeters of topsoil. However, cattle ranching and agriculture can deplete as much as 2 to 3 centimeters of topsoil every 25 years- 60 to 80 times faster than it can be replaced by nature.

        Salinization is a type of land degradation that involves an increase in the salt content of the soil. This usually occurs as a result of improper irrigation practices. The greatest Mesopotamian empires- Sumer, Akkad and Babylon- were built on the surplus of the enormously productive soil of the ancient Tigris-Euphrates alluvial plain. After nearly a thousand years of intensive cultivation, land quality was in evident decline. In response, around 2800 BC the Sumerians began digging the huge Tigris-Euphrates canal system to irrigate the exhausted soil. A temporary gain in crop yield was achieved in this way, but over-irrigation was to have serious and unforeseen consequences. From as early as 2400 BC we find Sumerian documents referring to salinization as a soil problem. It is believed that the fall of the Akkadian Empire around 2150 BC may have been due to a catastrophic failure in land productivity; the soil was literally turned into salt. Even today, four thousand years later, vast tracks of salinized land between the Tigris and Euphrates rivers still resemble rock-hard fields of snow.

        Soil erosion is another form of desertification. It is a self-reinforcing process; once the cycle of degradation begins, conditions are set for continual deterioration. As the vegetative cover begins to disappear, soil becomes more vulnerable to raindrop impact. Water runs off instead of soaking in to provide moisture for plans. This further diminishes plan cover by leaching away nutrients from the soil. As soil quality declines and runoff is increased, floods become more frequent and more severe. Flooding washes away topsoil, the thin, rich, uppermost layer of the earth’s soil, and leaves finer underlying particles more vulnerable to wind erosion. Topsoil contains the earth’s greatest concentration of organic matter and microorganisms, and is where most of the earth’s land-based biological activity occurs. Without this fragile coat of nutrient-laden material, plan life cannot exist. An extreme case of its erosion is found in the Sahel, a transitional zone between the Sahara Desert and the tropical African rain forests; home to some 56 million people. Overpopulation and overgrazing have opened the hyperarid land to wind erosion, which is stripping away the protective margin of the Sahel, and causing the desert to grow at an alarming rate. Between 1950 and 1975, the Sahara Desert spread 100 kilometers southward through the Sahel.

The word “leaching” in paragraph 5 is closest in meaning to _________.

Note 45

SỰ KẾT HỢP TỪ VỚI CÁC DANH TỪ THÔNG DỤNG

 Advice

-    follow/ take/ listen to/get on sb’s advice (nghe theo lời khuyên của ai)

-    get/ obtain/ receive advice (nhận lời khuyên)

Bill

-    pay/ settle/ pick up a bill (trả một hóa đơn)

-    be landed with/ face a bill (chịu một hóa đơn)

-    an unpaid bill (một hóa đơn chưa thanh toán)

Career

-    at the height/ peak of one’s carreer (ở đỉnh cao sự nghiệp)

-    embark on a career (dấn thân vào một nghề)

-    have a careeer in (có sự nghiệp trong lĩnh vực)

-    climb the career ladder (thăng tiến nghề nghiệp)

-    week/ ruin one’s career (hủy hoại sự nghiệp của mình)

-    a promising/ brilliant career (sự nghiệp đầy hứa hẹn)

Chance

-    get/have a chance (có cơ hội)

-    give/ offer/ provide a chance (tạo cơ hội)

- jump at/ seize/ grab a chance (nắm lấy cơ hội)

-    not stand a chance of doing sth (không có khả năng làm gì)

-    sheer/ pure chance (sự tình cờ hoàn toàn)

-    good/ fair/ high/strong chance (khả năng cao)

-    minimal/ slight/ little chance (khả năng mong manh)

Demand

-    meet/ satisfy/cope with a demand (đáp ứng/ thỏa mãn nhu cầu)

-    increase/ boost/ stimulate demand (tăng nhu cầu)

-    big/ huge/ great/ considerable/ enormous/ strong demand (nhu cầu lớn/ cao)

Difference

-    make a difference (tạo ra/ mang sự khác biệt)

-    make all the difference (thay đổi lớn)

-    tell the difference (phân biệt)

-    feel/ know/ notice/ see/ perceive/ the difference (cảm nhận, nhận thức sự khác biệt)

-    considerable/ enormous/ profound/ dramatic/ sharp difference (sự khác biệt đáng kể, rõ rệt)

-    with a difference (đặc biệt khác thường)

Difficulty

-    have/ experience/ encounter/ face/ get into/ run into difficulties (gặp khó khăn)

-    do sth with/ without difficulty (làm gì một cách khó khăn/ dễ dàng)

-  solve/ cope with/ deal with difficulties (giải quyết khó khăn)

-    overcome/ surmount difficulties (vượt qua khó khăn)

-    great/ enormous/ considerabke/ serious difficulty (khó khăn lớn, nghiêm trọng)

Fault

-    find/ locate/ identify/ discover fault (tìm lỗi)

-    correct/ fix/ repair/ recify a fault (sữa chữa một lỗi)

-    be all/ entirely one’s own fault (hoàn toàn do lỗi của ai)

-    be hardly one’s own fault (hầu như không phải lỗi của ai)

-    at fault (chịu trách nhiệm về một sai lầm)

Favour

-    do sb a favour (làm giúp ai điều gì)

-    ask a favour (hỏi xin một ân huệ)

-    owe sb a favour (mang ơn ai)

-    return a favour (đáp lại một ân huệ)

-    find/ gain/ win favour (có được sự ủng hộ)

-    in favour of sth (ủng hộ, tán thành cái gì)

Habit

-    be in/ have the habit of (có thói quen)

-    form/ get into/ fall into/ make/ develop/ acquire a habit (hình thành, tạo thành một thói quen)

-    change a habit (thay đổi một thói quen)

-    break/ give up/ get out of a habit (bỏ một thói quen)

-    by habit (do thói quen)

-    out of habit (vì thói quen)

Measure

-    adopt/ take/ implement/ impose/ inưoduce a measure (thực hiện/ áp dụng một giải pháp)

-    appropriate/ effective/ necessary/ practical measure (giải pháp thích hợp/ hiệu quả/ cần thiết thực tế)

-  short-term/ temporary measure (giải pháp tạm thời)

Occupation

-    follow/ take up an occupation (theo một nghề)

-    choose an occupation (chọn một nghề)

-    give up one’s occupation (bỏ nghề)

Opportunity

-    have/ find/ get an opportunity (có/ tìm được một cơ hội)

-    have ample/ considerable/ plenty of opportunity (có nhiều cơ hội)

-    have limited/ little/ not much opportunity (có ít cơ hội)

-    a good/ great/ wonderful/ golden opportunity (cơ hội tốt, cơ hội tuyệt vời, cơ hội vàng)

Problem                      .

-    encounter/ be faced with/ confront/ be confronted with/ face a problem (gặp phải một vấn đề)

-    solve/ deal with/ clear up/ overcome/ address/ tackle a problem (giải quyết/ vượt qua một vấn đề)

-    big/ great/ serious/ acute problem (vấn đề lớn/ nghiêm trọng)

Popularity

-    gain/ grow/ enjoy popularity (ngày càng được ưa thích)

-  at the peak of sbV sth’s popularity (ở đỉnh cao của sự nổi tiếng)

-    an increase/ a rise in popularity (sự ưa chuộng, gia tăng)

-    a decline/ drop in popularity (giảm/ ít nổi tiếng)

Relationship

-    have/ enjoy a close/ good relationship (có mối liên hệ gần gũi/ tốt)

-    build (up)/ develop/ establish/ foster a relationship (xây dựng/ thiêt lập mối quan hệ)

-    improve/ strengthen a relationship (cải thiện, củng cố mối quan hệ)

Standard

-    set a Standard (đưa ra, lập ra một tiêu chuẩn)

-    meeư achieve/conform to/ comply with standards (đáp ứng, đảm bảo tiêu chuẩn)

-    raise/ improve standards (nâng cao/ cải thiện chất lượng)

Subject

-    bring up a subject (đưa ra một đề tài)

-   

Nhắn tin Zalo