超声波气体流量计Ultrasonic gas flowmeter工作原理working principle： 在管道的一侧或两侧嵌置

A、准确度高（0.5级），能满足天然气贸易交接计量的要求High accuracy (0.5 level), can meet the requirements of natural gas trade handover measurement

B、适用的流量范围大Applicable flow range is large

C、直管段较短，节省占地面积The straight section is shorter, saving the floor space

D、由于气体超声波流量计无移动部件，无压力损失，无磨损，无潜在泄漏，因此维护量小。Because the gas ultrasonic flowmeter has no moving parts, no pressure loss, no wear, no potential leakage, so the maintenance amount is small

A、标准孔板流量计Standard orifice flowmeter

B、涡轮流量计turbine flowmeter

C、涡街流量计vortex flowmeter

D、气体腰轮流量计gas waist flowmeter

E、气体罗茨流量计gas roots flowmeter

F、超声波流量计ultrasonic flowmeter.

A、超声波换能器ultrasonic transducer

B、电子转换线路Electronic switching circuit

C、流量显示累积系统Flow display accumulator system

D、以上都不对

A. 16～20000

B. 100k～100k

C. 500k～5000k

简述DANIEL超声波流量计的工作原理。