承担本地网片区基站代维服务要求:基站代维人员中具有通过中国电信基站代维人员技能认证的应不少于总人数的()。
A.50%
B.60%
C.70%
D.80%
参考答案:B
There is still a ___________ doubt among them as to the practical value of the building. [ ]
A. specific
B. sure
C. some
D. certain
染色时固定的作用是什么?