How do you put surreptitious in a sentence?

1. The surreptitious meeting took place in a secluded corner of the park.

2. She cast a surreptitious glance at the man standing in the shadows.

3. The spy used surreptitious methods to gather intelligence.

4. The company conducted surreptitious research to develop a new product.

5. He made a surreptitious attempt to steal the document from her desk.