Prepositions often confused

In for Within.
Don’t say:   I’ll come back in an hour – if you mean before the end of an hour.
Say: I’ll come back within an hour.
In means after the end of, within means before the end of.
Use of certain prepositions
Propositions of Place
TO and AT
Use TO for movement from one place to another. Example: I walk to school every day.
Use AT to denote position or rest. Example:  He’s waiting at the door.
IN denotes position or rest inside something. Example: The pencil is in the box.
INTO denotes movement towards the inside of. Example: They walk into the room.
Prepositions of Time
Use AT with the exact time.
Example: She arrived at 8 o’clock in the morning.
Use ON with days and dates.
Examples:  On Sunday we go to church. My birthday is on the third of December.
Use IN with a period of time.
Example:  In summer the weather is warm.

After for In.
Don’t say:   I may be able to go after a week.
Say: I may be able to go in a week.
Or: I may be able to go in a week’s time.
When speaking of a period of time in the future, use in, and not after. Here in means after the end of.

 From for
Don’t say:   Ian’s been  ill  from last  Friday.
Say: Ian’s been ill since last Friday.
Place the preposition since before words or phrases denoting a point in time: since Monday, since yesterday, since eight o’clock, since Christmas. When we use since, the verb is usually in the present perfect tense, but it may be in the past perfect: I was glad to see Tom. I hadn’t seen him since last Christmas.
Note: From can also denote a point in time, but it must be followed by to or till: He works from eight o’clock till one o’clock without a break.

Since for For.
Don’t say:   She’s lived here since two years
Say:   She’s lived here for two years.
Place the preposition for before words or phrases denoting  a period of time: for three  days,  for six weeks, for two years,  for a few  minutes,  for a long time.  Use it with any tense except the present.
Note:  For is often omitted. We can Say:  I’ve been here for two years or I’ve been  here two years.

For for
Don’t say:   The  teacher  spoke for bad  habits,
Say: The  teacher spoke about bad habits.
Don’t  use for in  the sense of about. The chief  use of for is to convey the idea of  being  in  favour  of.  If  we  say  that  the  teacher  spoke  for bad habits  it’s like saying  that heshe spoke  in  favour  of  bad  habits!

From for Of or In.
Don’t say:    He’s the tallest from all  the boys.
Say: He’s the tallest of all the boys.
Or: He’s the tallest boy in the class.
Precede adjectives (or adverbs) in the superlative degree by the and follow them by of or in.

From for By.
Don’t say:    Mary’ was punished from  her father.
Say:  Mary was punished by  her father.
Use by (not from) after the passive form to show the doer of the action.

By for With.
Don’t say:   The man shot the bird by a gun.
Say: The man shot the bird with a gun.
When you warn to show the means or the instrument with which the action is done, use with. By denotes the order of the action: The bird was shot by the man.
Note: The following take by and not with: by hand, by post, by phone, by one’s watch, by the hour, by the dozen, by the metre.

Except for Besides As well as
Don’t say:   I have other books except these.
Say: I have other books besides as well as these  (= in addition to these).
Note: Except means to leave out: Everyone was present except John.

Don’t say:    Charlie was standing just besides me.
Say:  Charlie was standing just beside me.

Don’t say:    Divide the apple between you three.
Say: Divide the apple among you three.
Use between for two only. Use among for more than two.

Between and (a)  Between.
Don’t say:   There was  a fight among two boys.
Say: There was a fight between two boys.

In and (a) In.
Don’t say:   Gemma  spent all the  day into her room.
Say: Gemma spent all the day in her room.
(b) Into.
Don’t say:   Richard  came  in the room  and sat  down.
Say: Richard came into the room and sat down.
In denotes position inside something, while into denotes motion or direction towards the inside of something.
Note: Always write the preposition into as one word.

On, At, (Time.) (a) On.
Don’t say:   My uncle will arrive at Saturday.
 Say: My uncle will arrive on Saturday.
(b)  At.
Don’t say:    I usually get up on seven  o’clock.
Say: I usually get up at seven o’clock.
(c) In.
Don’t say:   She goes for a  walk at the  afternoon.
Say: She goes for a walk in the afternoon.
(1) Use on with the days of the week or month’ on Friday, on March 25, on New Year’s Day.
(2) Use at with the exact time: at four o’clock, at dawn, at noon, at sunset, at midnight. (3) Use in with a period of time  in April, in winter, in 1945, in the morning. Also at night and by day.

 For and At. (Price.) (a)
Don’t say:   I bought  a  book at fifty  pence.
Say:  I  bought  a  book  for fifty pence.
(b)  At.
Don’t say:   I can’t buy it for such a high price.
Say: I can’t buy it at such a high price.
Use for if the actual sum is mentioned  use at if the actual sum isn’t given
Note: If the weight or measure follows the price, use at with the actual sum: That velvet is available at £5 a metre.

To and Till. (a)
Don’t say:  We walked  till  the  river  and  back.
Say: We walked to the river and  back.
(b) Till.
Don’t say:    I’ll stay here to next month.
Say:  I’ll  stay here  till   next month.

In and At. (a)
Don’t say:   Liam has a flat at Paris.
Say:  Liam has a flat in  Paris.
We use in to describe the physical location  of something as part of a larger thing or place.
(b) At.
Don’t say:   My mother is staying in 66 Argyle Street.
Say: My mother is staying at 66 Argyle Street.
We use at when we’re talking about an address, a public place or building (a bus stop, the Post Office, the library etc.) and cases in which the location is irrelevant but what we do there is what matters (school, the dentist, dance class etc.)

To and At. 

(a) To.
Don’t say:    We come at school every morning,
Say: We come to school every morning.
(b) Don’t say:  Someone is standing to the door.
Say: Someone is standing at the door.