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.

  The air above our head is becoming cleaner. A breath of fresh air has been running right round the planet for the past five years. The planet is apparently purging itself of pollution. Paul Novell of the University of Colorado, the co-author of a report on this phenomenon says, “It seems as if the planet’s own cleaning service has suddenly got a new lease of life. Suddenly, there are a lot of changes going on up there”.

  Estimates of the death toll from urban smog have been steadily rising, so the new cleaner trend could have significant consequences for life expectancy in cities as well as for the planet itself. The sudden and unexpected reversal of several decades of worsening pollution extends from the air in city streets to the remotest mid-Pacific Ocean and Antarctica.

   Among the pollutants which have begun to disappear from the atmosphere are carbon monoxide, from car exhaust and burning rain forests, and methane from the guts of cattle, paddy fields, and gas fields. Even carbon dioxide, the main gas behind global warning, has fallen slightly.

   There are two theories about why pollution is disappearing. First that there is less pollution to start with due to laws to cut down urban smogs and acid rain starting to have a global impact. Second, that the planet may be becoming more efficient at cleaning up.

   The main planetary clean-up agent is a chemical called hydroxyl. It is present throughout the atmosphere in tiny quantities and removes most pollutants from the air by oxidizing them. The amount of hydroxyl in the air has fallen by a quarter in 1980s. Now it may be reviving for two reasons: ironically, because the ozone hole has expanded, letting in more ultraviolet radiation into the lower atmosphere, where it manufactures hydroxyl. Then the stricter controls on vehicle exhausts in America and Europe may have cut global carbon monoxide emissions, thereby allowing more hydroxyl to clean up other pollutants.

Question: Based on information in the passage, all of the following information referring to hydroxyl is true EXCEPT __________.

Ever since it was first possible to make a real robot, people have been hoping for the invention of a machine that would do all the necessary jobs around the house. If boring and repetitive factory work could be (1)_____ by robots, why not boring and repetitive household chores too?

          For a long time the only people who really gave the problem their attention were amateur inventors And they came up against a major difficulty. That is, housework is actually very complex It has never been one job it has always been many. A factor robot (2)_____ one task endlessly until it is reprogrammed to do something else. It doesn’t run the whole factory. A housework robot on the other hand, has to do several different (3)_____ of cleaning and carrying jobs and also has to cope (4)______ all the different shapes and positions of rooms, furniture, ornaments, cats and dogs. (5)______ , there have been some developments recently. Sensors are available to help the robot locate objects and avoid obstacles. We have the technology to produce the hardware. All that is missing the softwarethe programs that will operate the machine.

Điền vào số 1

Ever since it was first possible to make a real robot, people have been hoping for the invention of a machine that would do all the necessary jobs around the house. If boring and repetitive factory work could be (1)_____ by robots, why not boring and repetitive household chores too?

          For a long time the only people who really gave the problem their attention were amateur inventors And they came up against a major difficulty. That is, housework is actually very complex It has never been one job it has always been many. A factor robot (2)_____ one task endlessly until it is reprogrammed to do something else. It doesn’t run the whole factory. A housework robot on the other hand, has to do several different (3)_____ of cleaning and carrying jobs and also has to cope (4)______ all the different shapes and positions of rooms, furniture, ornaments, cats and dogs. (5)______ , there have been some developments recently. Sensors are available to help the robot locate objects and avoid obstacles. We have the technology to produce the hardware. All that is missing the softwarethe programs that will operate the machine.

Điền vào số 4

Ever since it was first possible to make a real robot, people have been hoping for the invention of a machine that would do all the necessary jobs around the house. If boring and repetitive factory work could be (1)_____ by robots, why not boring and repetitive household chores too?

          For a long time the only people who really gave the problem their attention were amateur inventors And they came up against a major difficulty. That is, housework is actually very complex It has never been one job it has always been many. A factor robot (2)_____ one task endlessly until it is reprogrammed to do something else. It doesn’t run the whole factory. A housework robot on the other hand, has to do several different (3)_____ of cleaning and carrying jobs and also has to cope (4)______ all the different shapes and positions of rooms, furniture, ornaments, cats and dogs. (5)______ , there have been some developments recently. Sensors are available to help the robot locate objects and avoid obstacles. We have the technology to produce the hardware. All that is missing the softwarethe programs that will operate the machine.

Điền vào số 5

Ever since it was first possible to make a real robot, people have been hoping for the invention of a machine that would do all the necessary jobs around the house. If boring and repetitive factory work could be (1)_____ by robots, why not boring and repetitive household chores too?

          For a long time the only people who really gave the problem their attention were amateur inventors And they came up against a major difficulty. That is, housework is actually very complex It has never been one job it has always been many. A factor robot (2)_____ one task endlessly until it is reprogrammed to do something else. It doesn’t run the whole factory. A housework robot on the other hand, has to do several different (3)_____ of cleaning and carrying jobs and also has to cope (4)______ all the different shapes and positions of rooms, furniture, ornaments, cats and dogs. (5)______ , there have been some developments recently. Sensors are available to help the robot locate objects and avoid obstacles. We have the technology to produce the hardware. All that is missing the softwarethe programs that will operate the machine.

Điền vào số 2