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tuananh2006
2 năm trước
What is the main idea of paragraph 3?
A.Ecotourism threatens to destroy rainforests as well as -farming, logging, and mining.
B.While ecotourism damages them somewhat, it also protects natural places from destruction.
C.Tour guides need to educate tourists on the dangers of farming, logging, and mining.
D.Rare animals need to be protected from visitors taking them home to their countries.
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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 following question.
Water scarcity is fast becoming one of the major limiting factors in world crop production. In many areas, poor agricultural practices have led to increasing desertification and the loss of formerly arable lands: Consequently, those plant species that are well adapted to survival in dry climates are being looked at for an answer in developing more efficient crops to grow on marginally arable lands.
Plants use several mechanisms to ensure their survival in desert environments. Some involve purely mechanical and physical adaptations, such as the shape of the plant's surface, smaller leaf size, and extensive root systems. Some of the adaptations are related to chemical mechanisms. Many plants, such as cacti, have internal gums and mucilage which give them water-retaining properties. Another chemical mechanism is that of the epicuticular wax layer. This wax layer acts as an impervious cover to protect the plant. It prevents excessive loss of internal moisture. It also protects the plant from external aggression, which can come from inorganic agents such as gases, or organic agents which include bacteria and plant pests.
Researchers have proposed that synthetic waxes with similar protective abilities could be prepared based on knowledge of desert plants. If successfully developed, such a compound could be used to greatly increase a plant's ability to maintain health in such adverse situations as inadequate water supply, limited fertilizer availability, attack by pests, and poor storage after harvesting.
It can be inferred that synthetic stimulate waxes _________.
A.have not succeeded
B.have been determined to be impervious to organic and inorganic agents
C.have not been developed yet
D.have the quality of causing bacteria

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 following question.
Water scarcity is fast becoming one of the major limiting factors in world crop production. In many areas, poor agricultural practices have led to increasing desertification and the loss of formerly arable lands: Consequently, those plant species that are well adapted to survival in dry climates are being looked at for an answer in developing more efficient crops to grow on marginally arable lands.
Plants use several mechanisms to ensure their survival in desert environments. Some involve purely mechanical and physical adaptations, such as the shape of the plant's surface, smaller leaf size, and extensive root systems. Some of the adaptations are related to chemical mechanisms. Many plants, such as cacti, have internal gums and mucilage which give them water-retaining properties. Another chemical mechanism is that of the epicuticular wax layer. This wax layer acts as an impervious cover to protect the plant. It prevents excessive loss of internal moisture. It also protects the plant from external aggression, which can come from inorganic agents such as gases, or organic agents which include bacteria and plant pests.
Researchers have proposed that synthetic waxes with similar protective abilities could be prepared based on knowledge of desert plants. If successfully developed, such a compound could be used to greatly increase a plant's ability to maintain health in such adverse situations as inadequate water supply, limited fertilizer availability, attack by pests, and poor storage after harvesting.
Which is one of the ways in which the epicuticular wax protects the plant?
A.It guards against bacteria.
B.It helps the plant to avoid excessive moisture intake.
C.It releases gases against plant pests.
D.It helps the plant to attack aggressors.

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 following question.
Water scarcity is fast becoming one of the major limiting factors in world crop production. In many areas, poor agricultural practices have led to increasing desertification and the loss of formerly arable lands: Consequently, those plant species that are well adapted to survival in dry climates are being looked at for an answer in developing more efficient crops to grow on marginally arable lands.
Plants use several mechanisms to ensure their survival in desert environments. Some involve purely mechanical and physical adaptations, such as the shape of the plant's surface, smaller leaf size, and extensive root systems. Some of the adaptations are related to chemical mechanisms. Many plants, such as cacti, have internal gums and mucilage which give them water-retaining properties. Another chemical mechanism is that of the epicuticular wax layer. This wax layer acts as an impervious cover to protect the plant. It prevents excessive loss of internal moisture. It also protects the plant from external aggression, which can come from inorganic agents such as gases, or organic agents which include bacteria and plant pests.
Researchers have proposed that synthetic waxes with similar protective abilities could be prepared based on knowledge of desert plants. If successfully developed, such a compound could be used to greatly increase a plant's ability to maintain health in such adverse situations as inadequate water supply, limited fertilizer availability, attack by pests, and poor storage after harvesting.
The word “arable” in the first paragraph is closest in meaning to ________.
A.barren
B.marsh
C.fertile
D.parched

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 following question.
Water scarcity is fast becoming one of the major limiting factors in world crop production. In many areas, poor agricultural practices have led to increasing desertification and the loss of formerly arable lands: Consequently, those plant species that are well adapted to survival in dry climates are being looked at for an answer in developing more efficient crops to grow on marginally arable lands.
Plants use several mechanisms to ensure their survival in desert environments. Some involve purely mechanical and physical adaptations, such as the shape of the plant's surface, smaller leaf size, and extensive root systems. Some of the adaptations are related to chemical mechanisms. Many plants, such as cacti, have internal gums and mucilage which give them water-retaining properties. Another chemical mechanism is that of the epicuticular wax layer. This wax layer acts as an impervious cover to protect the plant. It prevents excessive loss of internal moisture. It also protects the plant from external aggression, which can come from inorganic agents such as gases, or organic agents which include bacteria and plant pests.
Researchers have proposed that synthetic waxes with similar protective abilities could be prepared based on knowledge of desert plants. If successfully developed, such a compound could be used to greatly increase a plant's ability to maintain health in such adverse situations as inadequate water supply, limited fertilizer availability, attack by pests, and poor storage after harvesting.
The word “extensive” in the second paragraph is closest in meaning to _________.
A.comprehensive
B.shallow
C.widespread
D.spongy

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