Add by + the doer only when it's useful or new information: This book was written by my grandmother. If the doer is unknown, obvious or unimportant, leave it out: The window was broken. Use with for a tool: It was opened with a knife.
This book was written by my grandmother.
Here the doer is the interesting part, so it goes at the end, where English puts new information.
| by + doer | Who did it, when that's new or important: The song was written by Ana. |
|---|---|
| with + tool | What was used: The door was opened with a key. |
| Nothing | The doer is unknown, obvious or unimportant: The bank was robbed. |
English puts new information at the end of the sentence. The passive with by moves the doer there.
This house was designed by a famous architect.
The doer is what you want the listener to notice.
The bank was robbed last night.
Leave the doer out. Don't add by someone.
The lock was opened with a screwdriver.
By is for the doer; with is for the tool or material used.
Common expressions worth learning as they are.
Romeo and Juliet was written _____ Shakespeare.
From the basic form to the reporting passive.
Paste an email or an essay. Clarigram marks the mistakes you actually make, shows the rule behind each one as a picture, and builds your practice from them.
Only when the doer is useful information: new, surprising or important. Most passive sentences in real English have no by-phrase at all.
English likes to put new or important information at the end of a sentence. The passive lets you move the doer there: The Mona Lisa was painted by Leonardo.