我国的数字同步网采用（）主从同步方式，按照时钟等级可分为（）。
参考答案：等级；四级
It’s better for you to take some time to prepare your annual (年度的) performance _____ carefully, which will decide whether you will get a promotion next year.
A．revision
B．remark
C．review
D．request
用来表示堆栈指针的寄存器是( )。
A．IP
B．BP
C．SP
D．SS
