Shetland is the last stronghold of otters in the British Isles.设得兰群岛是水獭在不列颠群岛上最后的栖息地。An attempt is being made to entice otters back to the river.人们正试图把水獭引诱回河里去.Otters are believed to have been on Earth for 90 million yea...
电磁波是由一种称为速调管的微波电子管产生的.The electronmagnetic wave is produced by microwave tubes called klystrons.这些工厂生产电子管 、 晶体管 、 收音机和电视机.These factories produce tubes, transistors, radio sets and TV sets.这些放大器是用微型电子管制成的.These amplifier...
Good afternoon to you, sir.下午好，先生Good afternoon, and welcome to our Career Day.下午好, 欢迎大家来到职业生涯节目.Mr. Hill: Good afternoon. I believe that this house is for sale.希尔先生: 下午好. 我想这房子是出售的吧?...