封闭式

The amphitheater was a sealed off round structure. Swordplay, wresting, gladiatoral and other contests were held there.

场为四周封闭结构，可以举行斗剑、格斗、斗兽及其他赛项目。

Silicon Electable Stove are heating instruments often used by factory mines,enterprises,hospitals,college labs.It has tno styles:Openingclosing.

封闭电炉为工矿、企业、医院、大中院校实验室常用的加热设备，分为开和封闭两种。

Bench of closed circuit cooling tower that is composed of boiler ,exchanger, orifice flowmeter, water pump, micromanometer , heat indicator and so on is established.

建立了锅炉、换热器、孔板流量计、水泵、微压计、温度计等仪器设备组成的封闭冷却塔实验台。