2011年英语四级考试模拟练习题及答案(2)

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　　Part II Reading Comprehension (Skimming and Scanning) (15minutes)
　　Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions on Answer Sheet 1. For questions 1-7, mark
# v  g& S  T$ N8 c3 \; r4 {　　Y (for YES) if the statement agrees with the information given in the passage;
' U3 ^7 ~% n, O0 x( L  l　　N (for NO) if the statement contradicts the information given in the passage;
　　NG (for NOT GIVEN) if the information is not given in the passage.
　　For questions 8-10, complete the sentences with the information given in the passage.
　　To Save Trees, Fighting One Alien Insect with Others
　　Rusty rhea sighs wistfully as he talks about the beauty and peace of standing amid a grove (小树林) of deep green hemlocks in Appalachia, some of them up to 160 feet (50 meters) tall and more than 500 years old.
　　"This is a very special tree," said Rhea, an entomologist for the U.S. Forest Service's Forest Health Protection program in Asheville, North Carolina, "I was brought up here, and I don't want to see another species go by the wayside."
6 n8 g9 K& O+ w# k9 T4 i　　The evergreen trees, a hallmark of southern Appalachia's national parks, are under attack by an invasive inse4ct barely visible to the eye but potent enough to fell the giants of the eastern United States' old-growth forests.
　　Already the tiny bug from Japan, known as the hemlock woolly adelgid (HWA), has killed upward of 95 percent of the hemlocks in Virginia's Shenandoah National Park. Now they are making their way through the half-million-plus-acre (200,000-plus-hectare) Great Smoky Mountains National Park in North Carolina and Tennessee.
　　The hemlocks shade streams, keeping water temperatures just right for brook trout (鲑鱼) and other fish. They also house birds such as the black-throated green warbler, solitary vireo, and northern goshawk, all three of which mainly shelter in stands of hemlock trees.
　　Because of the insect's broad impact on the entire ecosystem of southern Appalachia, HWA stands to cause wider damage than the American chestnut blight (枯萎病)of the early 1900s. That fungus from Europe killed off the once dominant chestnut trees from the northeast United States to the southern Appalachian Mountains.
- \2 P) S6 ], H6 c　　In addition, a species related to HWA, the balsam woolly adelgid, has already killed about 90 percent of the mature Fraser fir trees in the Smokies.
　　Acting Quickly
　　HWA arrived in the U.S. Pacific Northwest via nursery plants from Japan in 1924. By 1951 the tiny invader had been found in Virginia. Since then the insect has spread to more than 15 U.S. states.
' A+ \2 p4 z, Y　　The key to killing the HWA is to catch it early and act quickly. It's already well established in the Great Smoky Mountains, where Rhea and others are trying to stem the spread of the bugs.
' g1 u0 u) X) F2 T$ p　　HWA multiply quickly: All of the insects are females that reproduce asexually (无性地), laying several hundred eggs a year. When they get to the nymph, or crawler, stage, they are dormant from about June until October, after which they emerge and establish themselves on trees.
　　Winds and birds and other animals spread the crawlers through the forest.
　　HWA crawlers feed on the new growth of hemlocks by piercing the twigs that hold the branches, sucking the sap, and injecting toxic saliva. The needles turn from a deep green to a grayish green and eventually die, depriving the tree of nutrition from photosynthesis.
　　An infected tree usually dies within five years of initial attack. Infection is signaled by either a white, cottonlike material that appears along a tree's twigs or by the "baldness" of a tree's upper branches.