常見(jiàn)例句雙語(yǔ)例句Others have pointed out that it could be a vacuum-tube hearing aid, which was first sold in 1921.其他人指出那可能是個(gè)真空琯的助聽(tīng)器，助聽(tīng)器最早在1921年銷(xiāo)售。 返回 hearing-aid tube