Read the following article and select the best answer. Article: When children start kindergarten, evident gaps in science knowledge already exist between Whites and minorities and between youngsters from upper-income and low-income families. And they often deepen into significant achievement gaps by the end of eighth grade if they are not dealt with during elementary school. The findings suggest that, in order for the United States to maintain long-term scientific and economic competitiveness in the world, policymakers need to renew efforts to ensure access(n.,) to high-quality, early learning experiences in childcare settings, preschools and elementary schools. The researchers' study tracked 7,757 children from their start in kindergarten to the end of eighth grade. Researchers found that, among kindergarteners with low levels of general knowledge, 62 percent were struggling in science by the time they reached third grade and 54 percent were struggling in that subject in eighth grade. And general knowledge gaps between minorities and Whites were already large at the time when students began kindergarten. "Children growing up in low-income families typically experience comparatively fewer early opportunities to learn about the natural and social sciences," the authors wrote. "Their parents often have lower educational levels and therefore less science knowledge themselves as well as fewer resources available to direct the children's academic growth. Children raised in poverty often attend poorly resourced schools that futher limit their academic opportunities." Morgan said that, within families, parents who regularly talk and interact with toddlers can point out and explain physical, natural and social events occurring around them daily. This might help youngsters learn facts and concepts that will prepare them to take better advantage of science instruction they receive during elementary and middle school. Question: Which of the following can be the best title for the text? - Income Gaps Affect Children's School Performances - Provide More Available Access to Childhood Learning - Science Knowledge Gaps Are Obvious in Kindergarten - Equal Education Is Important in Kindergarten
Science Knowledge Gaps Are Obvious in Kindergarten

Read the following article and select the best answer. Article: Nearly all of today's Native Americans in North, Central and South America can trace their ancestry to just six women whose descendants immigrated around 20,000 years ago, a DNA study suggests. The finding does not mean that only these six women gave rise to migrants who crossed into North America from Asia in the earliest population of the continent.Rather, it suggests that only six left a particular DNA legacy that persists to today in about 95% of Native Americans, said study co-author Ugo Perego in Utah. "The women did not necessarily arrive together, nor even all live at the same time," he said.Results indicate the women arrived sometime between 18,000 and 21,000 years ago. The work was published this week by the journal PLoS One.Perego is from the Sorenson Molecular Genealogy Foundation in Salt Lake City and the University of Pavia in Italy.The work confirms the previous indications of just six maternal lineages, as well as a date of around 20,000 years ago when the first people in North America arrived after crossing a land bridge from Asia, Perego said. The researchers studied mitochondrial DNA, which is passed only from mother to daughter.They created a "family tree" that traces the different DNA _ found in today's Native Americans.By noting mutations in each branch and applying a formula for how often such mutations arise, they calculated how old each branch was.That indicated when each branch arose in a single woman. The six "founding mothers" obviously did not live in Asia because the DNA signatures they left behind are not found there, Perego said.So they probably lived in Beringia, the now-submerged land bridge that stretched to North America, he said. Question: What didn't Ugo Perego and his team do? - They used a "family tree" to analyze the findings. - They focused on life styles of the original women. - They clarified genetic changes in the family tree. - They studied how long each branch had developed.
They focused on life styles of the original women.

Q: Read the following article and select the best answer. Article: Tulou, the special residential architecture of Fujian Province was included on the UNESCO's World Heritage List during the 32ndsession of the World Heritage Committee in Quebec, Canada. In the fourth century, Han Chinese living in the Central Plains area began to migrate south, gradually gathering in Fujian and forming the Hakka communities. As a defence against enemies, the Hakkas chose to live in compact communities, and the tulou was their preferred houses. Tens of thousands of such earthen structures were constructed in Fujian Province. Most tulous are to be found in the valleys, surrounded by high mountains, and some are in the depths of the great mountains. Most are three to four stories high, and look like circular blockhouses . Rooms on the first floor are used as kitchens, rooms on the second floor are used as barns , and rooms on the third and fourth floors are for bedrooms and living rooms. For defensive purposes, the rooms on the first floor have no windows. Raw materials for the tulou were obtained locally. Their main building material was a mixture of clay, sand, lime and water, and egg whites, brown sugar and rice water were added as adhesive agents . It was then mixed to form the walls. Once they dried, the walls were so hard that driving a nail into them would have been difficult. Fir branches, which are extremely strong and do not rot, were used to strengthen them, and many centuries later they have remained their original look. Tulous are located in a region where earthquakes happen frequently, and their circular construction helps them resist the regular shocks. The proven design even inspired one famous Peruvian architect, who paid several visits to Yongding, to build a tulou back home. Not long after, an earthquake struck only 10 kilometers away, and while all the houses around the earthen building fell down, his tulou remained. Question: From the passage , we know that Tulou _ . - is a special residential architecture of Han Chinese in Fujian even today - was once the place where the Hakkas chose to live together - stands in the valleys and is also modern people's preferred houses - looks like circular blockhouses but easy to fall down in the earthquake
A: was once the place where the Hakkas chose to live together