Trong các chữ: T, O, Q, U, C,W, L, có bao nhiêu chữ có trục đối xứng:

A.2

B.3

C.4

D.5

Fill in each blank with a suitable preposition

51. I’m afraid we have run_________ of apple juice. Will an orange juice do?.

52. Since graduating _________ School, he has got very interested in environmental issues.

53. It was careless __________ him to leave the door open last night.

54. Mary is excited _________winning the prize

55. I think you should concentrate______________ your duty

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 36 to 42.

Scientists have uncovered a new threat to the world's endangered coral reefs. They have found that most are incapable of growing quickly enough to compensate for rising sea levels triggered by global warming. The study suggests that reefs - which are already suffering serious degradation because the world's seas are warming and becoming more acidic - could also become overwhelmed by rising oceans.

The research - led by scientists at Exeter University and published in Nature this week -involved studying growth rates for more than 200 tropical western Atlantic and Indian Ocean reefs. It was found only 9% of these reefs had the ability to keep up with even the most optimistic rates of sea-level rises forecast by the Intergovernmental Panel on Climate Change. "For many reefs across the Caribbean and Indian Ocean regions, where the study focused, rates of growth are slowing due to coral reef degradation," said Professor Chris Perry, of Exeter University. “Meanwhile, rates of sea-level rise are increasing - and our results suggest reefs will be unable to keep up. As a result, water depths above most reefs will increase rapidly through this century.”

Sea levels rose by several inches over the past century and measurements indicate the speed of this increase is now rising significantly. Two key factors are involved: climate change is making ocean water warmer and so it expands. And as ice sheets and glaciers melt, they increase amounts of water in the oceans.

At the same time, reefs are being weakened by ocean warming and also by ocean acidification, triggered as the seas absorb more and more carbon dioxide. These effects lead to bleaching events that kill off vast stretches of coral and limits their ability to grow.

“Our predictions, even under the best case scenarios, suggest that by 2100, the inundation of reefs will expose coastal communities to significant threats of shoreline change,” said co-author Prof Peter Mumby of Queensland University. This point was backed by US marine scientist Ilsa Ruffner writing in a separate comment piece for Nature. “The implications of the study are dire. Many island nations and territories are set to quickly lose crucial natural resources.”

What did scientists at Exeter University find in their research?

A. Tropical coral reefs are increasing more quickly than others in Pacific Ocean.

B. The majority of tropical coral reefs cannot keep pace with the increasing rate of sea levels.

C. Many coral reefs are developing in spite of their degradation.

D. The rapid rise in sea levels does not affect the density of coral reefs.

Cho u → 2018 ; 2019 và  A 1 ; 2 ; B − 2 ; 1 . Nếu T u → A = A ' ; T u → B = B ' , khi đó A’B’ có độ dài là:

A. 13

B. 5

C. 10

D. 2018

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 43 to 50.

It is estimated that over 99 percent of all species that ever existed have become extinct. What causes extinction? When a species is no longer adapted to a changed environment, it may perish. The exact causes of a species' death vary from situation to situation. Rapid ecological change may render an environment hostile to a species. For example, temperatures may change and a species may not be adapted. Food resources may be affected by environmental changes, which will then cause problems for a species requiring these resources. Other species may become better adapted to an environment, resulting in competition and, ultimately, in the death of a species.

The fossil record reveals that extinction has occurred throughout the history of Earth. Recent analyses have also revealed that on some occasions many species became extinct at the same time - a mass extinction. One of the best-known examples of mass extinction occurred 65 million years ago with the demise of dinosaurs and many other forms of life. Perhaps the largest mass extinction was the one that occurred 225 million years ago, when approximately 95 percent of all species died. Mass extinctions can be caused by a relatively rapid change in the environment and can be worsened by the close interrelationship of many species. If, for example, something were to happen to destroy much of the plankton in the oceans, then the oxygen content of Earth would drop, even affect organisms not living in the oceans. Such a change would probably lead to a mass extinction.

One interesting, and controversial, finding is that extinctions during the past 250 million years have tended to be more intense every 26 million years. The periodic extinction might be due to intersection of the earth's orbit with a cloud of comets, but this theory is purely speculative. Some researchers have also speculated that extinction may often be random. That is, certain species may be eliminated and others may survive for no particular reason. A species' survival may have nothing to do with its ability or inability to adapt. If so, some of revolutionary history may reflect a sequence of essentially random events.

In paragraph 3, the author makes which of the following statements about a species' survival?

A. it may depend on chance events.

B. it does not vary greatly from species to species

C. it reflects the interrelationship of many species.

D. it is associated with astronomical conditions.

Kể tên các tứ giác có trong hình dưới đây

A. Tứ giác DHIE, GHIF

B. Tứ giác DHIE, DGFE

C. Tứ giác HIGE, DHIE, DGFE

D. Tứ giác HIFG, DHIE, DGFE

An và Bình nhận làm chung một công việc. Nếu một mình An làm thì sau 3 giờ sẽ xong việc, còn nếu Bình làm một mình thì sau 6 giờ sẽ xong việc đó. Hỏi cả 2 người cùng làm thì sau mấy giờ sẽ xong việc đó?

Vì sao có sự song song tồn tại các nhóm sinh vật có tổ chức thấp bên cạnh các nhóm sinh vật có tổ chức cao?

A. Vì trong những điều kiện xác định, có những sinh vật duy trì tổ chức nguyên thuỷ của chúng hoặc đơn giản hoá tổ chức mà vẫn đảm bảo sự thích nghi thì vẫn tồn tại và phát triển.

B. Vì các sinh vật có tổ chức thấp vẫn không ngừng phát sinh.

C. Vì các sinh vật có tổ chức thấp không có nhu cầu nhiều về dinh dưỡng cho sự sinh trưởng và phát triển.

D. Vì các sinh vật có tổ chức thấp không có nhu cầu nhiều về năng lượng cho các hoạt động sống.