Đề thi thử THPT Quốc gia môn Tiếng Anh năm 2016 - THPT Hàm Long

All mammals feed their young. Beluga whale mothers, for example, nurse their calves for some twenty months, until they are about to give birth again and their young are able to find their own food. The behavior of feeding of the young is built into the reproductive system. It is a nonelective part of parental care and the defining feature of a mammal, the most important thing that mammals-- whether marsupials, platypuses, spiny anteaters, or placental mammals -- have in common.

But not all animal parents, even those that tend their offspring to the point of hatching or birth, feed their young. Most egg-guarding fish do not, for the simple reason that their young are so much smaller than the parents and eat food that is also much smaller than the food eaten by adults. In reptiles, the crocodile mother protects her young after they have hatched and takes them down to the water, where they will find food, but she does not actually feed them. Few insects feed their young after hatching, but some make other arrangement, provisioning their cells and nests with caterpillars and spiders that they have paralyzed with their venom and stored in a state of suspended animation so that their larvae might have a supply of fresh food when they hatch.

For animals other than mammals, then, feeding is not intrinsic to parental care. Animals add it to their reproductive strategies to give them an edge in their lifelong quest for descendants. The most vulnerable moment in any animal's life is when it first finds itself completely on its own, when it must forage and fend for itself. Feeding postpones that moment until a young animal has grown to such a size that it is better able to cope. Young that are fed by their parents become nutritionally independent at a much greater fraction of their full adult size. And in the meantime those young are shielded against the vagaries of fluctuating of difficult-to-find supplies. Once a species does take the step of feeding its young, the young become totally dependent on the extra effort. If both parents are removed, the young generally do not survive.

Mobile phones emit microwave radio emissions. Researchers are questioning whether exposure to these radio waves might (36) _______ to brain cancer. So far, the data are not conclusive. The scientific evidence does not (37) _______ us to say with certainly that mobile phones are categorically (38) _______. On the other hand, current research has not yet (39) _______ clear adverse effect associated with the prolonged use of mobile phones.

Numerous studies are now going (40) _______ in various countries. Some of the results are contradictory but others have shown an association between mobile phone use and cancer. (41) _______, these studies are preliminary and the issue needs further, long - term investigation.

(42) _______ the scientific data is more definite, it is prudent for people to try not to use mobile phone for long (43) _______ of time. Don't think that hands free phones are any safer either. At the moment, research is in fact showing the (44) _______ and they may be just as dangerous. It is also thought that young people (45) _______ bodies are still growing may be at particular risk.

In this era of increased global warming and diminishing fossil fuel supplies, we must begin to put a greater priority on harnessing alternative energy sources. Fortunately, there are a number of readily available, renewable resources that are both cost- effective and earth – friendly. Two such resources are solar power and geothermal power.

Solar energy, which reaches the earth through sunlight, is so abundant that it could meet the needs of worldwide energy consumption 6,000 times over. And solar energy is easily harnessed through the use of photovoltaic cells that convert sunlight to electricity. In theUSalone, more than 100, 000 homes are equipped with solar electric systems in the form of solar panels or solar roof tiles. And in other parts of the world, including many developing countries, the use of solar system is growing steadily.

Another alternative energy source, which is abundant in specific geographical areas, is geothermal power, which creates energy by tapping heat from below the surface of the earth. Hot water and steam that are trapped in underground pools are pumped to the surface and used to run a generator, which is produces electricity. Geothermal energy is 50, 000 times more abundant than the entire known supply of fossil fuel resources. And as with solar power, the technology needed to utilize geothermal energy is fairly simple. A prime example of effective geothermal use inIceland, a region of high geothermal activity where over 80 percent of private homes are heated by geothermal power.

Solar and geothermal energy are  just two of promising renewable alternatives to conventional energy sources. The time is long overdue to invest in the development and use of alternative energy on global scale.