Recently an unusually high number of evergreen trees, especially spruces and pines, started dying in parks in many areas of the northeastern United States. Some people proposed that a new herbicide-a chemical designed to eliminate weeds from grass lawns in parks and gardens-might be responsible for killing the trees. However, it seems unlikely that the herbicide is to blame for the tree die-off for several reasons.
Environmentally Safe Design
First, the new herbicide was specifically designed to be environmentally safe. Before the herbicide could be sold in the United States, it was tested by a government agency. This testing took years, and all the results showed that the herbicide did not have adverse environmental effects.
Uneven Pattern of Damage
Second, the damage to evergreen trees that has been observed is very uneven, In the parks where the herbicide is applied to control weeds, only some evergreen trees have experienced problems, while other trees have remained healthy. If the new herbicide really were responsible for damaging evergreen trees, we would expect to see much more consistent damage to trees in the areas where it has been used.
A More Likely Cause
Third, there is a much more likely cause for the damage to affected evergreen trees than the new herbicide. The problems all have occurred in a part of the United States that has experienced higher-than-average temperatures and prolonged droughts. The common and unavoidable environmental factors of heat and a lack of water are probably responsible for the evergreen trees' problems, not the new herbicide.
Summarize the points made in the lecture, being sure to explain how they challenge the specific points made in the reading passage.
The widespread die-off of evergreen trees in the northeastern United States has raised concerns about the potential role of a new herbicide. While the reading argues that the herbicide is unlikely responsible for the damage, the listening passage counters these claims by providing evidence that supports the herbicide’s role in tree deaths.
First, the reading claims that the herbicide was extensively tested and found environmentally safe by a government agency. The testing process took years and showed no adverse environmental effects. However, the listening challenges this by stating that most of the tests focused on the herbicide's safety for animals, such as household pets. While ensuring safety for animals is reasonable, the listening points out that very little testing was done to evaluate the herbicide’s impact on trees, leaving the possibility that the chemical is harmful to evergreens.
Second, the reading notes that the affected trees showed an uneven damage pattern in areas where the herbicide was used. It argues that if the herbicide were responsible, more consistent damage would be expected. In contrast, the listening explains that an uneven damage pattern is exactly what would result from the herbicide. Trees located in elevated areas remain healthy, while those in lower areas are damaged. This is because the herbicide dissolves in water, which accumulates in lower areas, affecting the roots of trees there while sparing trees in higher locations.
Third, the reading suggests that the damage is more likely caused by environmental factors, such as heat and prolonged drought, which have affected the northeastern United States. However, the listening refutes this by stating that damage caused by heat and drought typically begins with older leaves turning brown. The damaged trees, however, show new leaves turning brown, which indicates the cause is something other than heat or drought—likely the herbicide.
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