Is Ann ________?[ ]
A. their friends
B. her friend
C. your friends
D. his a friend
答案:B
血细胞计数池的深度是()
A.0.01mm
B.0.05mm
C.0.10mm
D.0.15mm
E.0.20mm
10kV设备不停电的安全距离为0.7米,35KV设备不停电的安全距离为1.0米,110KV设备不停电的安全距离为1.5米,220KV设备不停电的安全距离为()米。