火灾自动报警系统导线敷设后,应用500V绝缘电阻表测量每个回路导线对地的绝缘电阻,且绝缘电阻值不应小于()MΩ。
A.5
B.10
C.15
D.20
参考答案:D
Mary worked here as a ____ secretary and ended up getting a full-time job with the company.
A.pessimistic
B.temporary
C.previous
D.cautious
成人所需的必需氨基酸有
A.5种
B.6种
C.7种
D.8种
E.10种