HDSL系统可实现无中继传输()。
A.2~5km
B.3~6km
C.4~7km
D.5~8km
参考答案:B
— Jim study hard these days?
—Yes, he will (将) take an exam (考试) next week.
A.Is, have to
B.Does, have to
C.Can, have to
D.Does, has to
站间试压一般只进行()试验。
A.强度
B.严密性
C.渗透性
D.屈服