、两圆x2+y2－6x+16y－48=0与x2+y2+4x－8y－44=0的位置

C
Jiang Nan, a full-time mother in Beijing, keeps a dozen or so cloth bags at home, carefully selecting one or two before heading out to get groceries. “Most of them were giveaways from advertising marketing campaigns, but
others had been handed out in the street by various environmental protection organizations,” she explained.
Since June 2008 China has forbidden the production,
sale and usage of plastic bags thinner than 0.025 millimeter (毫米), and retailers(零售商) are not allowed to provide free plastic bags to their customers, regardless of the thickness.
Many Chinese consumers like Jiang have learned to refuse plastic bags whenever possible in their shopping. “A plastic bag may only cost a few jiao, but it’s more about how bad they are for the environment,” Jiang said.
The plastic ban is for the most part well carried out in big cities, and has been distinctly effective in reducing white waste. On the first anniversary of the plastic ban Global Village of Beijing, an NGO environmental organization, shows that during the year of the ban the consumption of plastic bags fell by about 40 billion pieces in chain supermarkets alone, saving more than 1.2 million tons of petroleum.
However, enforcement shows considerably less muscle in smaller cities, towns and country-
side. In a remote town like Lichuan, the awareness of environmental protection is not as strong as that in big cities. Street vendors(街头小贩) worry that they are likely to lose customers if they charge them for plastic bags. Seeing no significance in the issue, local government often turn a blind eye to banned bag traffic in the market.
There are still those who don’t have an interest in living green. Cui Lin, another Beijinger, often forgets to bring a cloth bag when shopping, and has to buy plastic bags. “Anyway I think plastic bags are neater and cleaner, and I don’t mind paying a couple more jiao,” he shrugged.
Mrs Yu, a vegetable vendor in Lichuan County, Jiangxi Province, recalled that before plastic bags became popular in the early 1990s, Chinese people always carried a bamboo basket when they visited the market. “Plastic bags are more convenient,” she comments, and her view might be that of the tens of millions of people in the nation who still cling to plastic bags, paid or free. This is suggested by her trade where piles of plastic bags are still passed out every day.
49. In Paragraph 1, the writer uses Jiang Nan’s case to __________.

A. introduce a topic	B. tell a story
C. describe a person	D. offer an argument

How did Jiang Nan get her cloth bags? 

A. She bought them at a low price. C. She borrowed them from her relatives.

B. She got them for free. D. She made them herself.

51. Which is NOT the reason why some people still use plastic bags when shopping?

A. Cloth bags are difficult to get and heavy to carry.

B. People’s awareness of environmental protection is not strong enough.

C. People don’t mind paying a couple more jiao for plastic bags.

D. Street vendors worry that they are likely to lose customers if they charge them.

52. What message does the writer mostly convey in the passage?

A. To reduce white waste is urgent.

B. The plastic bag ban has achieved great success.

C. There is still a long way to go for the plastic bag ban.

D. People’s awareness of environmental protection should be stressed.