1. The valuable jewels were kept under lock and key in the safe.
珍贵的珠宝被锁在保险箱里。

2. The confidential documents are always kept under lock and key.
机密文件始终被锁在抽屉里。

3. The medicine cabinet should be under lock and key to prevent children from accessing it.
药柜应该被锁起来，以防止孩子接触。

4. The keys to the office are under lock and key at all times.
办公室的钥匙随时都被锁起来。

5. The prisoner's cell is under lock and key to ensure he does not escape.
囚犯的牢房被锁起来，以确保他不会逃跑。

6. The museum's rare artifacts are kept under lock and key to protect them from theft.
博物馆的珍贵文物被锁起来，以保护它们免受盗窃。