A world-famous scientist，Dr．Halogen，was on his way to give another lecture．This particular night，his driver ___1___（ask） him for a favor．“Dr．Halogen，when you speak，everyone gives you honor and attention．I’d really like to see what that ____2_____（feel） like．Could we exchange clothes just for tonight? You’ll be the driver and I ____3____（be） the scientist．”

       Dr．Halogen，laughed and said，“Do you really think you can do it? What if someone asks you a difficult question?”

“I can answer it” said the driver．“I __4____（hear） you speak on this topic many，many times．”

“All right．” said the scientist，“it is April Fool’s Day after all!”

The two exchanged clothes and continued on to the meeting．When they arrived，the bogus（假冒的）scientist _____5____（receive） warmly．He gave a good speed and answered a few questions．Then a woman asked a very tricky one．Thinking quickly，he said，“Ma’am，that question has a very simple answer．It’s so easy，I’m going to let my driver，who __6___（sit） in the back now，___7____（explain） it!”