初学者线程问题

thread t=new thread(new threadstrat(countdown()));
if ((t.threadstate&threadstate.aborted)==threadstate.aborted)
     console.write("aborted");
if((t.threadstate&threadstate.background)==threadstate.background)
     console.write("background");........
我知道t.threadstate是返回t线程的状态他有10个值(unstarted running waitsleepjoin ....)
但这里的t.threadstate&threadstate.aborted是什么意思?? == 右边的t.threadstate&threadstate.aborted又是什么意思?  为什么不是t.threadstate==threadstate.aborted??? 还有每次输入关键字开头要大写有的中间也要大写,如何利用快捷键直接显示关键字(如:console)我是初学者见笑了