secret joint

例句：

1. 1. The two countries have been secretly negotiating for months.
   两国已经秘密谈判了几个月。
2. 2. They made a secret joint to avoid detection.
   他们做了一个秘密接头以避免被发现。
3. 3. The meeting was held in a secret joint to ensure privacy.
   会议在一个秘密接头中举行以确保隐私。