阅读下面的短文，请根据短文后的要求答题（请注意问题后的字数要求）

阅读下面的短文，请根据短文后的要求答题（请注意问题后的字数要求）
[1]Online advertising is simply advertising that is done on the Internet. While it has a much shorter history than traditional advertising, the effects of online advertising can not be undervalued As more people turn to the Internet as a source for daily news, socialization and communication, more advertising dollars are likely to be spent. In fact, in a period of five years, from 2006 to 2010, online advertising______ 6 percent of all money spent for advertising, to 12 percent or more.
[2]Online advertising is also quickly becoming a serious force for other types of advertising media to deal with. Newspapers and magazines all over the world are facing a number of different challenges, including loss of ad revenue (广告收益). Many attribute (把……归于) some of those struggles to online advertising, which is not only taking a share of the advertising, but a share of the audience as well.
[3]However, newspapers and magazines are not the only media dealing with lower revenue. The remarkable thing about online advertising is it gives the ads a much wider coverage and its globally wider coverage helps in making the advertisements reach more audiences. Furthermore, because of hypertext (超文本) linking, advertisers have the power to transport potential buyers directly to their site.
[4]Online advertising can be presented in many flexible styles. In some cases, it may not look like advertising at all. There was one case. A video that showed popcorn (爆玉米花) being popped by radiation which was put out from mobile phones was put on the website. While this was later revealed as a trick, the company that put the video online received a large amount of attention. The company sold earphones meant to help limit an individual’s exposure to radiation.
小题1:What is the main idea of the text? (no more than 7 words)
___________________________________________________ .
小题2:Fill in the blank in Paragraph 1 with proper words. (no more than 3 words)
____________________________________________________ .
小题3:Complete the following statement with proper words according to Paragraph 2. (within 5 words)
Traditional types of advertising media such as newspaper and magazines are suffering ___________ because of the serious force of online advertising.
小题4:List two benefits of online advertising. (no more than 20 words)
①_____________ ② ______________ .              
小题5:What does the underlined word “it” in Paragraph 4 refer to? (withan 3 words)
_______________________________________ .