Complete the following sentences according the passage. (请用书上的表达) 1. Google is the world's most popular _________________________________. 2. Google went public ___________ it began to sell advertising on the website. 3. Google is now a billion-dollar company and has been named ___________________ to work for in the United States. 4. Google's employees work in places where employees are ______________________ at their work. 5. Google has become the internet leader in terms of ______________ on the web.