搜题请搜索小程序“爱下问搜题”
问题 单项选择题

舒巴坦与青霉素联用，能产生明显的抗菌协同作用，其原因为

A．它能增强青霉素的耐酸性
B．可抑制β-内酰胺酶
C．可结合PBPs，与青霉素联合杀菌
D．可抑制细菌二氢叶酸还原酶
E．能改变细菌胞壁通透性

答案

参考答案：B

单项选择题

The fact that most Americans live in urban areas does not mean that they reside in the center of large cities. In fact, more Americans live in the suburbs of large metropolitan areas than in the cities themselves.
The Bureau of the Census regards any area with more than 2,500 people as an urban area, and does not consider boundaries of cities and suburbs.
According to the Bureau, the political boundaries are less significant than the social and economic relationships and the transportation and communication systems that integrate a locale. The term used by the Bureau for an integrated metropolis is an MSA, which stands for Metropolitan Statistical Area. In general, an MSA is any area that contains a city and its surrounding suburbs and has a total population of 50,000 or more.
At the present time, the Bureau reports more than 280 MSAs, which together account for 75 percent of the U.S. population. In addition, the Bureau recognizes 18 megapolises, that is, continuous adjacent metropolitan areas. One of the most obvious megapolises includes a chain of hundreds of cities and suburbs across 10 states on the East Coast from Massachusetts to Virginia, including Boston, New York, and Washington D. C. In the Eastern Corridor, as it is called, a population of 45 million inhabitants is concentrated. Another megapolis that is growing rapidly is the California coast from San Francisco through Los Angeles to San Diego.

The underlined word "integrate" in Paragraph 3 is closest in meaning to ______.

A．benefit

B．define

C．unite

D．restrict
查看答案
单项选择题

大庆油田首先从（）开始捞油方式研究和现场捞油试验。

A、萨尔图油田

B、老区油田

C、中区油田

D、外围油田
查看答案