零件的几何要素，按存在的状态分为理想要素和实际要素；按在形位公差中所处的地位分为被测要素和基准要素；按几何特征分为（）和（）。
参考答案：轮廓要素;中心要素
(100) whether to go with a shared or switched fast LAN technology once you start to max out your shared Ethernet of token-ring LAN is tough call. Users and analysts involved in (101) high-speed LANs have learned the benefits of each. However, there are trade-offs to each, and (102) which fast LAN technology to choose is critical for (103) network performance problems and (104) costly purchasing mistakes.
103（）
A.avoiding
B.clipping
C.choosing
D.deciding
E.dissolving
F.ensuring
G.evolving
H.implementing
I.Knowing
J.solving
电容器构架间的水平距离不应小于0.5m，每台电容器之间的距离不应小于（）电容器的铭牌应面向通道。
A、40mm
B、50mm
C、60mm
D、70mm
