题目

单位圆中弧长为1的弧所对圆心角的正弧度数是（  ） A．          B．1               C．        D．不能确定 答案：B 131. --- Here , your new computer is ready. --- Thank you. --- ______ to call this number if you have any problems. You’re free            B. It is free            C. Feel free           D. Don’t forget