听力题 Human population near the equator have evolved dark skin over many generations because of exposure to the fiercest rays of the sun. A similar phenomenon has also occurred in other parts of the animal kingdom. The African grass mouse is a good example. Most mice are nocturnal, but the African grass mouse is active during daylight hours. This means that it spends its days searching for food in the semi-dry bush in squired habitats of eastern and southern Africa. Its furry stripe''s like a chipmunk''s, which helps it blend in with its environment. Because it spends a lot of time in the intense tropical sun, the grass mouse has also evolved two separate safeguards against the sun''s ultraviolet radiation. First, like the population of humans in this region of the world, the skin of the grass mouse contains lots of melanin, or dark pigment. Second and quite unusual, this mouse has a layer of melanin pigmented tissue between its skull and skin. This unique cap provides an extra measure of protection for the grass mouse and three other types of African mouse, like rodents that are active during the day. The only other species scientists have identified with the same sort of skull of that occasion is the white camp-making bat of the Central American tropic. Although these bats sleep during the day, they do so curled up with their head exposed to the sun. Human population near the equator have evolved dark skin over many generations because of exposure to the fiercest rays of the sun. A similar phenomenon has also occurred in other parts of the animal kingdom. The African grass mouse is a good example. Most mice are nocturnal, but the African grass mouse is active during daylight hours. This means that it spends its days searching for food in the semi-dry bush in squired habitats of eastern and southern Africa. Its furry stripe''s like a chipmunk''s, which helps it blend in with its environment. Because it spends a lot of time in the intense tropical sun, the grass mouse has also evolved two separate safeguards against the sun''s ultraviolet radiation. First, like the population of humans in this region of the world, the skin of the grass mouse contains lots of melanin, or dark pigment. Second and quite unusual, this mouse has a layer of melanin pigmented tissue between its skull and skin. This unique cap provides an extra measure of protection for the grass mouse and three other types of African mouse, like rodents that are active during the day. The only other species scientists have identified with the same sort of skull of that occasion is the white camp-making bat of the Central American tropic. Although these bats sleep during the day, they do so curled up with their head exposed to the sun.

单选题The water of (the) Atlantic, Pacific, and Indian Oceans (make up)70.8 percent (to) the Earth's (surface).

单选题An unconsolidated aggregate of silt particles is also termed silt, ___________ a consolidated aggregate is called siltstone.

单选题In the nineteenth-century United States, It was assumed that growth, change, and progressive derived mainly from individual effort and competition

单选题Coral formations have known as fringing reefs are located close to shore, separated from land only by shallow water.

单选题Listening5"BiologyClass"

单选题Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points. This passage discusses the reasons and effects of human migration. ● ● ● Answer ChoicesA. Genetic studies play a very important role in helping modern humans find out where they have come from.B. Migration helped create humans, conquer the planet and shape our societies.C. Human beings could adapt to different conditions with their tools and language.D. Migration is big, dangerous, and compelling.E. Migration is the dynamic undertow of population change.F. Human beings' great events are connected with migration.

单选题The word "executing" in line 28 is closest in meaning to

单选题The word "it" in line 13 refers to

单选题The word "flourished" in line 11 is closest in meaning to

单选题(Some fish) have whiskers, which are sensory organs used (for touching) and tasting, and which (are helpful) when (are they) searching for food in sand and mud.

单选题Whatdoesthestudentneedfromthelibrary?

单选题The word "stunning" in line 24 is closest in meaning to (a) predictable (b) impressive (c) famous (d) gradual

单选题Documentary evidence supports claims that ______ the New World about AD 1000.

单选题The author mentions tulip growing in New Netherland. Pennsylvania. and Michigan in order to illustrate how

单选题Philosophy is (the study) of the nature of reality, knowledge, (existent), and (ethics) (by means) of rational inquiry. A. the study B. existent C. existent D. by means

单选题Narrator Listen to part of a conversation between two students. Now get ready to answer the questions. You may use your notes to help you answer.

单选题The common barn owl, one of ten species of barn owls found in North America, is also called the monkey-faced owl because its heart-shaped face looks — of a monkey.