What's the difference between 'Except' and 'Except for'?

[Anonymous]

I looked it up in a dictionary, but I still cant understand
the difference.

Help me with this.

And
_______extreme situations, makeups
for the two exams and the final must be
arranged at least one week in advance.

I can't use 'except' in this sentence, can I?
Why is that?

[MikeNewYork]

I looked it up in a dictionary, but I still cant understand
the difference.

Help me with this.

And
_______extreme situations, makeups
for the two exams and the final must be
arranged at least one week in advance.

I can't use 'except' in this sentence, can I?
Why is that?

"Except" and "except for" have different meanings. A good place to start is with a dictionary that defines both. This is from the AHD:

ex·cept (ĭk-sĕpt')
prep.
With the exclusion of; other than; but: everyone except me.

conj.
If it were not for the fact that; only. Often used with that: I would buy the suit, except that it costs too much.
Otherwise than: They didn't open their mouths except to complain.
Unless: “And ne'er throughout the year to church thou go'st/Except it be to pray against thy foes” (Shakespeare).

v., -cept·ed, -cept·ing, -cepts.

v.tr.
To leave out; exclude: An admission fee is charged, but children are excepted.

v.intr.
To object: Counsel excepted to the court's ruling.

idiom:
except for

Were it not for: I would join you except for my cold.

In your sentence, you want to create an exception for "extreme circumstances". That is where we use "except for" or "except in".