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Put the verbs in correct form
The earth (go) around the sun.
___________________
điền 1 từ thích hợp vào chỗ trống We are destroying the Earth. THe seas and rivers are(1)......... dirty to swim in. There is too(2).........smoke in the air in many cities in the world. We are cutting(3)............too many trees. We(4)..........burning the forests. We are also destroying(5).............of plants and(6)..........Many areas(7)...........Earth are wasteland.Farmers in many parts of the world cannot (8).....enough to eat.In some countries(9)........is too little rice.THe Earth is...
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điền 1 từ thích hợp vào chỗ trống
We are destroying the Earth. THe seas and rivers are(1)......... dirty to swim in. There is too(2).........smoke in the air in many cities in the world. We are cutting(3)............too many trees. We(4)..........burning the forests. We are also destroying(5).............of plants and(6)..........Many areas(7)...........Earth are wasteland.Farmers in many parts of the world cannot (8).....enough to eat.In some countries(9)........is too little rice.THe Earth is in (10)...........Save the Earth!
Next week when there ____________ a full moon, the ocean tides will be higher.
A. will be
B. will have been
C. is being
D. is
He is exhausted. He _______ around the whole afternoon trying to clean the house before the guests arrive.
A. has been running
B. has run
C. be running
D. was running
He is exhausted. He ______ around the whole afternoon trying to clean the house before the guests arrive.
A. has been running
B. has run
C. be running
D. was running
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. Biological diversity has become widely recognized as a critical conservation issue only in the past two decades. The rapid destruction of the tropical rain forests, which are the ecosystems with the highest known species diversity on Earth, has awakened people to the importance and fragility of biological diversity. The high rate of species ext...
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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 questions from 35 to 42.
Biological diversity has become widely recognized as a critical conservation issue only in the past two decades. The rapid destruction of the tropical rain forests, which are the ecosystems with the highest known species diversity on Earth, has awakened people to the importance and fragility of biological diversity. The high rate of species extinctions in these environments is jolting, but it is important to recognize the significance of biological diversity in all ecosystems. As the human population continues to expand, it will negatively affect one after another of Earth’s ecosystems. In terrestrial ecosystems and in fringe marine ecosystems (such as wetlands), the most common problem is habitat destruction. In most situations, the result is irreversible. Now humans are beginning to destroy marine ecosystems through other types of activities, such as disposal and runoff of poisonous waste; in less than two centuries, by significantly reducing the variety of species on Earth, they have irrevocably redirected the course of evolution.
Certainly, there have been periods in Earth’s history when mass extinctions have occurred. The extinction of the dinosaurs was caused by some physical event, either climatic or cosmic. There have also been less dramatic extinctions, as when natural competition between species reached an extreme conclusion. Only 0.01 percent of the species that have lived on Earth have survived to the present, and it was largely chance that determined which species survived and which died out.
However, nothing has ever equaled the magnitude and speed with which the human species is altering the physical and chemical world and demolishing the environment. In fact, there is wide agreement that it is the rate of change humans are inflicting, even more than the changes themselves, that will lead to biological devastation. Life on Earth has continually been in flux as slow physical and chemical changes have occurred on Earth, but life needs time to adapt-time for migration and genetic adaptation within existing species and time for the proliferation of new genetic material and new species that may be able to survive in new environments.
The author mentions the reduction of the variety of species on Earth in line 7-8 to suggest that
A. humans are often made ill by polluted water
B. new habitats can be created for species
C. some species have been made extinct by human activity
D. understanding evolution can prevent certain species from disappearing
_______ appear, they are really much larger than the Earth
A. Small as the stars
B. The stars as small
C. As the small stars
D. Despite of the small stars
_______ appear, they are really much larger than the Earth.
A. Small as the stars
B. The stars as small
C. As the small stars
D. Despite of the small stars
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.Life in the UniverseExobiology is the study of life that originates from outside of Earth. As yet, of course, no such life forms have been found. Exobiologists, however, have done important work in the theoretical study of where life is most likely to evolve, and what those extrateưestrial life forms might be like.What sorts of planets are most l...
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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 questions from 35 to 42.
Life in the Universe
Exobiology is the study of life that originates from outside of Earth. As yet, of course, no such life forms have been found. Exobiologists, however, have done important work in the theoretical study of where life is most likely to evolve, and what those extrateưestrial life forms might be like.
What sorts of planets are most likely to develop life? Most scientists agree that a habitable planet must be terrestrial, or rock-based, with liquid surface water and biogeochemical cycles that somewhat resemble Earth’s. Water is an important solvent involved in many biological processes. Biogeochemical cycles are the continuous movement and transformation of materials in the environment. These cycles include the circulation of elements and nutrients upon which life and the Earth’s climate depend. Since (as far as we know) all life is carbon-based, a stable carbon cycle is especially important.
The habitable zone is the region around a star in which planets can develop life. Assuming the need for liquid surface water, it follows that most stars around the size of our sun will be able to sustain habitable zones for billions of years. Stars that are larger than the sun are much hotter and bum out more quickly; life there may not have enough time to evolve. Stars that are smaller than the sun have different problem. First of all, planets in their habitable zones will be so close to the star that they will be “tidally locked” – that is one side of the planet will always face the star in perpetual daylight with the other side in the perpetual night. Another possible obstacle to life on smaller stars is that they tend to vary in their luminosity, or brightness, due to flares and “star spots”. The variation can be large enough to have harmful effects on the ecosystem.
Of course, not all stars of the right size will give rise to life; they also must have terrestrial planets with the right kind of orbits. Most solar systems have more than one planet, which influence each other’s orbits with their own gravity. Therefore, in order to have a stable system with no planets flying out into space, the orbits must be a good distance from one another. Interestingly, the amount of space needed is roughly the width of a star’s habitable zone. This means that for life to evolve, the largest possible number of life-supporting planets in any star’s habitable zone is two.
Finally, not all planets meeting the above conditions will necessarily develop life. One major threat is large, frequent asteroid and comet impacts, which will wipe out life each time it tries to evolve. The case of Earth teaches that having large gas giants, such as Saturn and Jupiter,.in the outer part of the solar system can help keep a planet safe for life. Due to their strong gravitation, they tend to catch or deflect large objects before they can reach Earth
What is the topic of the passage?
A. The search for intelligent life
B. Conditions necessary for life
C. Characteristics of extraterrestrial life
D. Life in our solar system