_____ late for school again. [ ]
A. Not be
B. Don't is
C. Dont't be
D. Don't
答案:C
图中既是肾单位的组成部分,又属于循环系统结构的是
A.①
B.②
C.③
D.④
同一移动网内的本地呼叫接通率为()
A.≥90%
B.≥85%
C.≥80%
D.≥75%