奥巴马梦想与责任：

Hello, everybody! Thank you. Thank you. Thank you, everybody. All right, everybody go ahead and have a seat. How is everybody doing today? (Applause.) How about Tim Spicer? (Applause.) I am here with students at Wakefield High School in Arlington, Virginia. And we’ve got students tuning in from all across America, from kindergarten through 12th grade. And I am just so glad that all could join us today. And I want to thank Wakefield for being such an outstanding host. Give yourselves a big round of applause.

在这一段话里All right, go ahead分别是什么意思？，在How is everybody doing today?中doing是什么意思？