We all know that in English, there are two voices for a verb: the active voice and the passive voice .
The passive voice is widely used in various circumstances. To my best knowledge, it can be used to:
- describe a situation where the subject who conducts the action is not to be disclosed, or simply unknown, or already known by the public, or not significant to be mentioned, etc. For example:
- US security system was seriously challenged in the event of 911.
- I was given a $100 for my 1st day work in the supermarket.
- create a very object tune as the subject is missing. This is quite common in scientific writings.