这个不算牛，牛的是当年比尔写完Basic解释程序后，保罗带去演示，结果半路发现忘记写引导程序，就在飞机...
I want to learn asl and it’s hard to find apps to teach good. Sadly I’m still looking because the kids and some adults are very sloppy and do not know asl themselves but are trying to teach us. I would not get this app unless you already know sign quite a bit. Very disappointed...