n.气体检验器...

He had unscrewed the caps most of the way.他已经快把螺丝帽拧下来了。She unscrewed the cap of her water bottle and gave him a drink.她拧开水瓶盖，让他喝了一口。The Officer unscrewed the cap and put the bottle to his nostrils.那位官员拧开了瓶盖,把瓶子凑近鼻孔....