Inthe listening material, the professor made several points about the invasion ofthe zebra mussels can be stopped.
Firstof all, the reading passage states that the human transportation will cause theinvasion of the zabra mussels, while the professor contradicts that people cannotcontrol it in the past because of the lack of the knowledge. On the other hand,the ocean water will be taken by the ship to replace the freshwater, which maykill the mussels.
Moreover,the reading passage also mentions that if the mussels are taken to the newplace, they won't have predators, while the professor refutes that they candominate it just for a short time. They will be a new food source for birds, sothey can not dominant in the end.
Furthermore,the reading passage then talks that the invasion of the mussels will cause thedecline in the fish population in its area, while the professor departs from itthat it is true that mussels have negative impact in plankton. But for otherfish, mussels provide nutrition for fish at the bottom of the lake.
Thisis the entirely opposed to the writer's expectation.
Inthis listening material, the professor states several points about global cooling caused by the Little Ice Age.
First,the reading material states that after the ocean currents melted, the glaciersproduce an enormous number of cold freshwater into the Gulf Stream. This actioninfluenced the earth’s climate strongly, while the professor in the listening material disagrees that the cooling water just affected Europe and parts ofNorth America, but it can’t explain global cooling, or the cooling in southernarea.
Second,the reading material says that the volcanic eruption caused the Little Ice Ageas they generate dark clouds with dust and sulfur gas into our atmosphere whichwill reduce the earth’s temperature. By contrast, the professor contradictsthat the volcanic eruption produce colorful clouds and gases, but those gasesare not strong enough to decrease the earth’s temperature.
Lastly,the reading material mentions that the decrease of human population affect theearth’s temperature indirectly because we no longer cut substantial number oftrees and let the forest grow freely, these trees absorb carbon dioxide andthat will reduce the earth’s temperature. However, the professor objects thatpeople still cut a large number of trees and the short cease of deforestationis not long enough to cause the global cooling.