Directions：Complete the following passage by filling in each blank with one word that best fits the context.

Search engines are a type of computer program. The links that you get are not classified by subject. These engines search the Internet for you based 1_______ the key words you type in, 2______choose web pages for you 3_____contain the words you ask for. The contents they search have not been evaluated. This means that the information has never been checked—it could be reliable, true information 4_____ false information written by a person 5_____ qualifications or someone who does not have solid facts. 6_____links you obtain from the search engine go to full articles or pages. This requires 7_____ to be patient as you have to read the information to decide whether it is linked to 8____ you are searching. Examples of famous search engines are Google, Yahoo and Baidu. You can also go to the www.thesearchenginelist.com website and check their list of search engines.

乾隆皇帝曾对法国产生浓厚的兴趣，打算派外交使团会见路易十六。这一计划最终付诸东流，原因可能是： [ ]

A．法国发生了大革命

B．清廷忙于抗击沙俄入侵

C．中国正在和英使签订两国通商协议

D．普法战争爆发