门静脉高压症行分流术或断流术的主要目的是A．改善肝功能 B．预防和控制食管胃底曲张静

It’s not only humans that flourish in large settlements. Some ants find urban life so accommodating that their populations explode and they form supercolonies in cities.

"One of the most common house ant species might have been built for living in some of the smallest spaces in a forest, but the ants have found ways to take advantage of the comforts of city living," Purdue University said in a statement. Grzegorz Buczkowski, a Purdue University research assistant professor of entomology, discovered odorous house ants live in supercolonies, creating complex networks entomologists have never seen with the species before now. He found that odorous house ant colonies become larger and more complex as they move from forest to city and act somewhat like an invasive species, the university said. "The ants live about 50 to a colony with one queen in forest settings but explode into supercolonies with more than 6 million workers and 50 000 queens in urban areas," the university explained.

"This is a native species that’s doing this," said Buczkowski, whose results are published in the early online version of the journal Biological Invasions. "Native ants are not supposed to become invasive. We don’t know of any other native ants that are outcompeting other species of native ants like these," Buczkowski said. Odorous house ants live in hollow acorn shells in the forest. They’re called odorous because they have a coconut (椰子)-or rum-like smell when crushed. They’re considered one of the most common house ants, Purdue said. In semi-natural areas that are a cross of forest and urban areas, such as a park, Buczkowski said he observed colonies of about 500 workers with a single queen. "It’s possible that as the ants get closer to urban areas they have easier access to food, shelter and other resources," he said.

"In the forest, they have to compete for food and nesting sites," Buczkowski said. "In the cities, they don’t have that competition. People give them a place to nest, food to eat. " Buczkowski observed the ants in three different settings on and around the Purdue campus. He said it might be expected that if the odorous house ants were able to multiply into complex colonies, other ants would do the same. But Buczkowski found no evidence that other ants had adapted to new environments and evolved into larger groups as the odorous house ants have, Purdie said. "It’s possible that odorous house ants are better adapted to city environments than other ant species or that they had somehow outcompeted or dominated other species," he said. "This raises a lot of questions we’d like to answer. " Buczkowski said understanding why the supercolonies form could lead to better control of the pests in homes, as well as ensuring that they don’t outcompete beneficial species.

Future studies on odorous house ants will include studying the ant’s genetics and trying to understand the effects of urbanization of odorous house ants, Purdue said.

The purpose of understanding the supercolonies’ forming is to （）

A. control the pests and protect beneficial species

B. understand the effects of urbanization of ants

C. help study the ant’s genetics

D. better totally dominate other species

体育教学评价结构的基本构成原因不包括（）。

A.为什么评

B.谁来评

C.评什么

D.何时评

什么是账号电话卡业务？

铁的直接还原度

任务层次分析的步骤有（）。

A.确认任务类型

B.分析工作过程

C.任务层次分析的结

D.查证或者确认初步列出的任务清单

E.确认任务重要程度