1创建一个打印循环的线程 2创建二个打印循环的线程 3用临界区来处理二个打印循环的线程 4用互斥体来处理2个打印循环的线程 5用信号量来处理2个打印循环的线程-1 create a printed circulation threads 2 create two print circulation threads 3 by the critical area to deal with two print ci