Over
Used to indicate movement from one place to another:
- Come over to my house for dinner sometime.
- Could you roll over?
- They sent over a gift for his promotion.
Used to indicate movement downward:
- The big tree fell over on the road.
- Can you bend over and get the dish for me?
- He pushed it over the edge.
Used to indicate more than an expected number or amount:
- This amount is over our prediction.
- Kids twelve and over can watch this movie.
- The phone rang for over a minute.
Used to indicate a period of time:
- I worked there over a year.
- She did not sleep there over this past month.
By
Used to indicate proximity:
- Can I sit by you?
- He was standing by me.
- The post office is by the bank.
Used to indicate the person that does something in a passive voice sentence:
- The microwave was fixed by the mechanic.
- The flowers were delivered by a postman.
- The branch office was closed by the head office.
Used to indicate an action with a particular purpose:
- You can pass the exam by preparing for it.
- I expressed my feeling toward her by writing a letter.
- She finally broke the record by pure effort.
Used to indicate a mean or method:
- Please send this package to Russia by airmail.
- I came here by subway.