slackening of iron core

例句：

1. 1.The muscles in my neck are slackening as I sit here.
   我坐在这里，脖子的肌肉开始松弛。
2. 2.As the day wears on, the tension in the room begins to slacken.
   随着时间的流逝，房间里的紧张气氛开始放松。
3. 3. The economy is showing signs of slackening, which worries investors.
   经济显示出放缓的迹象，这让投资者担忧。