zhè / zhǒng / shuāng / jí / jīng / tǐ / guǎn / cháng / yòng / yú / fàng / dà / wēi / ruò / de / diàn / xìn / hào这种双极晶体管常用于放大微弱的电信号。This bipolar transistor is often used to amplify weak electrical signals.