He heard a sound from behind.

He is learning Greek.

The signal turned red, so I stopped crossing the road.

He is studying Japanese grammar.

He can speak Min Nan.

Don't forget to bring your mess tin when you go camping.

He met his death quietly.

This data is encoded, so special software is needed to decode it.

He created a program to encode the message.

He is a computer security expert, well-versed in the process of decryption.