电磁流量变送器工作中出现输出信号越来越小的主要原因是导管内壁沉积污垢、电极绝缘逐渐变坏。
参考答案:对
_____ your parents are not at home. What should you do? [ ]
A. Try
B. Be supposed
C. Suppose
D. Think
简述在建工程评估的几种方法及其评估思路。