More than 20 Internet service providers in China have joined hands to crack_down_on junk mail that has long plagued（折磨, 使苦恼）e-mail users in China by establishing a coordinated （协调）group, the China Daily reported Tuesday．
The union, connecting such big fish as Sina and 263．net, has agreed to share information on technical solutions, promote public involvement and extend international cooperation, said the newspaper．
The group was collecting information from netizens（网民） on junk e-mail addresses and contents．
"We will then examine the information, leading to the formation of a blacklist that can help block spam （垃圾邮件）sources," Jiang said．
He added that software solutions will also be developed to make it easy for net users to block and delete spam themselves．
But some Internet experts voiced warning, saying junk mail problems will continue to appear in the years ahead, according to the newspaper．
"There are still loopholes（漏洞） in legal, managerial and technological terms which have not yet been patched up," said Qing Sihan, an information security technology specialist from the Chinese Academy of Sciences．
China has had surprising growth in Internet users with their number reaching 45．8 million by this June, ranking the second largest cyber community in the world after the United States, according to the paper．
But netizens are increasingly attacked with junk e-mails．
On average, a Chinese net user is troubled by 350 junk e-mails each year．One out of every two e-mails they receive is spam, according to China Internet Network Information Center．
1．The underlined phrase “crack down on”（in Paragraph 1）probably means “__________．”
A．make full use of B. take severe measures against
C．get rid of D．make a careful study of
2．The group was collecting information from netizens on junk e-mail addresses and contents to __________．
A．ask for international cooperaton B. put the trouble-makers in prison
C．prevent the spread of junk e-mail D．warn people of the danger of using Internet
3．From the passage we know that__________．
A．Sina and 263．net keep many big fish
B．Sina and 263．net are big Internet service providers
C．China owns the largest Internet user in the world
D．very few e-mails that people receive are spam