与状态检修相比,计划检修的缺点有()。
A.维护费用高
B.维护工作量大
C.无法及时发现潜在故障
D.不利于供电安全
参考答案:A, B, C
His brother was born __________ May, 1981. [ ]
A. in
B. at
C. to
D. on
()发自膈下动脉。
A.肠系膜上动脉
B.肾上腺上动脉
C.肾上腺中动脉
D.肾上腺下动脉
E.腰动脉