文档介绍：several group number, then with b ± a, =c,c is is methyl b two vertical box between of accurate size. Per-2~3 measuremen商务相关的资料
搜索关键词：e-commerce OR "electronic commerce" OR e-business
注1：百度不支持OR，在Google使用，OR必须大写
注2：为了防止混淆，应该使用括号()，如在例1中。
③：site:
功能：在特定网站搜索
举例1：查看本空间有多少网页被Google收录
搜索关键词：site: /_xerox_
举例2：在维基百科Wikipedia上查找关于中国的资料
搜索关键词：China site:
注1：site:后面应去掉 ://
注2：通过“网页快照”，可以访问被运营商屏蔽的网站，比方Wikipedia
④：filetype:
功能：搜索特定格式的文档，比方pdf、doc、ppt……
举例：搜索环境问题的论文
搜索关键词：environment problem filetype:pdf
注1：百度支持关键词filetype:all，即所有文档类型，但Google不支持
注2：偷懒的话，filetype:pdf可以用关键词pdf代替，当然搜索结果就不一定是pdf文档了
several group number, then with b ± a, =c,c is is methyl b two vertical box between of accurate size. Per-2~3 measurement, such as proceeds of c values are equal and equal to the design value, then the vertical installation accurate. For example a, b, and c valueswhile on horizontal vertical errors for measurement, General in iron angle code bit at measurement level points grid errors, specific method is from baseline to methyl vertical box center line distance for a,, to b vertical box distance for b, list can measured
several group number, then with b ± a, =c,c is is methyl b two vertical box between of accurate size. Per-2~3 measurement, such as proceeds of c values are equal and equal to the design value, then the vertical installation accurat