Prepositions: OVER vs. ABOVE

Native speakers of English usually find it very difficult to explain the difference between the prepositions over and above, but nevertheless have very clear intuitions about when each should be used. Today's post will be getting into some detail about the factors driving these intuitions. The system is quite beautiful in its logic and very revealing about semantic structure.

Prepositions and time: FOR vs. SINCE

Use for to introduce durations like 1 second, 3.8 billion years, a long time and a little while.

Life on Earth has existed for about 3.8 billion years.
I listened to a Lady Gaga song for a little while.

Since is used to introduce the point in time when something became true and must always be used with a form of the perfective have.

I have lived on Earth since 1975.
I have been listening to Lady Gaga since 3 o'clock.

Some common mistakes involving since:

WRONG: I have lived here since 30 years. [You can't use a duration with since]
WRONG: I am living here since 1981. [You must use since with a form of have]

See the tag prepositions for related posts.

A conversation at noon

Tenses and aspect are among the most difficult things to learn in any language, so I've made a pretty chart to simplify the whole thing. It includes an example of a conversation that includes each form at least once.

Click to enlarge!

UPDATE:
It helps if you look at which time phrases you can use with each form (left side of the chart). For example:

The race started at 10am. [the simple past]
The race has started now. [has is present tense, so it is about the past of the present (i.e., a time before now)]
The race had started at 11am. [had is past tense, so it is about the past of the past (i.e., a time before 11am)]

If it is now 12pm, you can't say:

WRONG: The race has started at 10am. [has is present tense, but 10am is in the past, so it doesn't make sense]

If you want to attach a time phrase to start instead of have, use the simple past form.

Prepositions and time: BY vs. UNTIL

[For German speakers]
The German word bis can be translated into English as either by or until, which makes it hard to know which to use. Here is the answer.

Short version
Use by when talking about an event that occurs at a single point in time like finishing.

I will finish the project by Friday

Use until when talking about an activity or state that continues over a period of time like working (an activity) or being asleep (a state).

I will work until 10pm
I was asleep until the phone rang

Prepositions and places: IN, AT, ON

The U.S. president lives in The White House at number 1600 on Pennsylvania Avenue in the city of Washington in the District of Columbia in the United States on Earth. If these are all places, why does English need three different prepositions (in, at and on) to introduce them? Fortunately, the answer follows from general rules about when each of these prepositions should be used.