接力切换与其它切换最根本的区别在于它采用了（）（开环、闭环）预同步技术。
参考答案：开环
单项选择。
—Can I speak to your mom, please? — .[ ]
A. Sure, mom is reading the newspaper. Please hold on.
B. What are you doing?
C. Mom can speak to you.
甲队单独装修需要15天，乙队单独装修需要20天．甲、乙两队一起做，10天能不能装修完吗？
