问一个很简单的英语问题

问一个很简单的英语问题
[00:00.49]Look, Scott.
[00:02.09]This is a photograph I took during my trip to Australia.
[00:06.32]Let me see it, Mike.
[00:08.46]This is a good photograph.
[00:10.73]Who are these people?
[00:12.61]They're people I met during the trip.
[00:15.46]That's the ship we travelled on.
[00:17.97]What a beautiful ship!
[00:20.08]Who's this?
[00:21.60]That's the man I told you about.
[00:24.03]Remember?
[00:25.39]Ah yes.
[00:27.01]The one who offered you a job in Australia. That's right.
[00:31.89]Who's this?
[00:33.41]Guess!
[00:34.61]It's not you, is it? That's right.
[00:38.45]I grew a beard during the trip.
[00:41.03]but I shaved it off when I came home.
[00:44.32]Why did you shave it off?
[00:46.52]My wife didn't like it!
上文中:That's the man I told you about.句中的about是不是介词?
Why did you shave it off?中的off是什么词,是不是副词?