There _______ broccoli on the plate. [ ]
A. are many
B. is much
C. are much
D. is many
答案:B
凝结水电导率仪指示值偏高,应首先检查()。
A、电源是否稳定
B、仪表样水流量是否正常
C、电导电极常数是否正确
D、离子交换树脂是否失效
金属线槽的接地有什么具体要求?