gas-tight shell

例句：

1. 1. The gas-tight lid keeps the food fresh for hours.
   这个密封的盖子能让食物保持新鲜几个小时。
2. 2.The car was gas-tight, so there was no chance of leaking.
   这辆车密封得很好，所以没有泄漏的可能。
3. 3.The balloon was gas-tight, and it stayed inflated for a long time.
   气球密封得很好，长时间保持充气状态。