小区制可以用有限的()可以服务多个小区。
A.时隙
B.空间
C.码字
D.频谱
参考答案:D
When a pencil is partly in a glass of water, it looks as if it ______.
A.breaks
B.has broken
C.were broken
D.had been broken
适任考试成绩自理论考试和实际操作考试相应科目均合格后()年内有效。
A.1
B.2
C.3
D.4