ISUP部分是七号信令系统的第()级。
参考答案:4
The students are cleaning their classroom. ______ are cleaning the chairs.
And ______ are cleaning the windows. [ ]
A. Some; others
B. Some; another
C. Other; the others
D. Other; some
担保物权具有( )和( )。
A.从属性
B.强制性
C.时间性
D.不可分性