triad dot tube

例句：

1. 1. The triad dot tube is used in the electronics industry for signal amplification.
   三联管在电子工业中用于信号放大。
2. 2. The scientist discovered a new type of triad dot tube that could improve energy efficiency.
   科学家发现了一种新类型的三联管，可以提高能源效率。
3. 3. The triad dot tube was used to connect two circuits together in the old days.
   三联管在旧时代被用来连接两个电路。