1 . It is reported that half the world’s forests have already been destroyed. This widespread destruction is due to deforestation (采伐森林). Deforestation is the removal of a forest or group of trees where the land is later transformed to a non-forest use. Cutting down trees is necessary for man’s survival. However, deforestation has a number of negative effects on the environment and needs to be controlled.
There are two main purposes for cutting down trees and one of them is to use the trees as resources. Essential items like paper, furniture and charcoal are all made from trees. Deforestation is also carried out to clear land for farming and to make room for roads and houses. As the population grows, more of the forest has to be cleared.
Although deforestation is necessary up to a point, it has some negative effects on the environment. Firstly, cutting down forests destroys animal habitats, leaving them with no place to live in. Deforestation also allows erosion to occur, which leaves the land easy to landslides and makes it difficult for plants to grow there. Finally, the removal of trees also worsens air pollution. Trees act as natural air filters that change carbon dioxide into oxygen. When they are removed, carbon dioxide can build up and pollute the atmosphere. Hence, it is obvious that deforestation harms the environment.
Due to the harm deforestation causes, it is necessary to control it. There are a number of ways to do this. One of them is to make better use of farming land. That means we do not need as much land for farming, and hence do not need to cut down so many trees. There must also be laws to limit deforestation and these laws must be enforced strictly. On top of that, reforestation must be carried out systematically. This method involves planting new trees and plants in areas where deforestation has occurred to replace what was destroyed.
To sum up, although deforestation must be carried out, it can harm the environment and must be controlled. Beyond a certain point, this damage to the environment cannot be fixed. Hence, we should do our best to make sure that the damage is never too great to fix.
1. What is the second paragraph mainly about?| A．How people get farmland. |
| B．What trees mean to human beings. |
| C．Why people carry out deforestation. |
| D．What effect deforestation has on environment. |
| A．Homelessness. | B．Extinction. | C．Disease. | D．Wars. |
| A．By replacing new trees. | B．By banning deforestation. |
| C．By passing laws to limit farmland. | D．By making the best of farmland. |
| A．Carbon dioxide will pollute the atmosphere. |
| B．There will not be any forest left in the world. |
| C．The damage to the environment will be beyond repair. |
| D．People will have no trees as resources for essential items. |
2 . In times of stress, particularly when the water gets too warm, the coral(珊瑚)erupts the algae(海藻), and the coral turns white, causing a state called coral bleaching(漂白). Just a few degrees of heat can lead to coral bleaching, putting the coral on a path to starvation and death.
Driven by climate change, marine heat waves are becoming one of the greatest threats to the existence of coral, which is important to the ocean ecology. But in some rare good news researchers have discovered coral can recover from bleaching even before a heat wave ends, suggesting it has the potential to survive long heat waves. Coral was thought to survive only if a heat wave lasted just a few weeks.
But no one had studied this process during a longer heat wave. Then in 2015, Julia Baum, a marine ecologist at the University of Victoria, began a survey of two common species: brain and star coral around Kiritimati in the central Pacific Ocean. They checked the condition of the coral as the heat wave struck and disappeared.
Starting in May 2015, the temperature rose about 1 ℃ within 2 months. As expected, coral that housed heat-sensitive algae bleached sooner than those housing the heat-tolerant kind of algae. As the water continued to warm, even heat-tolerant algae erupted.
Many brain and star coral on Kiritimati recovered from bleaching while the water was still unusually warm. Baum said, "The unexpected recovery provides new hope, because it means that even under lasting heat waves, there's a path forward for some of them."
An unusual feature of the recovery is that brain coral that started out with heat-sensitive algae had a higher survival rate(82%)than coral that began with heat-tolerant algae(25%). "That finding is surprising," said Baum, expecting that heat-tolerant algae would be better suited for helping coral survive a heat wave. But during a longer heat wave, it might be more advantageous to start with a heat-sensitive algae.
1. What results in coral bleaching?| A．The white algae. | B．The coral's death. |
| C．An attack of waves. | D．A rise in ocean temperature. |
| A．To prove that coral can stop climate change. |
| B．To study how coral bleaching comes about. |
| C．To figure out whether coral survives long heat waves |
| D．To explain why coral bleaching is a big threat to coral |
| A．Ashamed. | B．Confused |
| C．Worried. | D．Astonished. |
| A．Protect the ocean environment. | B．Reduce coral bleaching. |
| C．Grow more different algae. | D．Regulate the heat wave. |
