后期复苏（ALS）的内容包括哪些（） A.不需要继续BLS B.借助专用设备和技术建

人机系统的( )主要取决于人机功能分配的合理性、机器的本质安全性及人为失误状况。

A．安全性
B．选择性
C．适用性
D．合理性

电力系统中，330kV并联电抗器的容量和台数选择，下列哪个因素是可不考虑的？（）

A.限制工频过电压

B.限制潜供电流

C.限制短路电流

D.无功平衡

1.Secure Net (SN) manufacture security cards that restrict access to government owned buildings around the world.The standard cost for the plastic that goes into making a card is $4 per kg and each card uses 40g of plastic after an allowance for waste. In November 100,000 cards were produced and sold by SN and this was well above the budgeted sales of 60,000 cards.The actual cost of the plastic was $5·25 per kg and the production manager (who is responsible for all buying and production issues) was asked to explain the increase. He said ‘World oil price increases pushed up plastic prices by 20% compared to our budget and I also decided to use a different supplier who promised better quality and increased reliability for a slightly higher price. I know we have overspent but not all the increase in plastic prices is my fault’The actual usage of plastic per card was 35g per card and again the production manager had an explanation. He said ‘The world-wide standard size for security cards increased by 5% due to a change in the card reader technology, however, our new supplier provided much better quality of plastic and this helped to cut down on the waste.’SN operates a just in time (JIT) system and hence carries very little inventory.Required:

(a) Calculate the total material price and total material usage variances ignoring any possible planning error in the figures. (4 marks)

简述循环氢压缩机入口流量不足的原因分析。