turn on fan for long

WB: If we can't say
-I have received your letter for 5 days,
then when the meaning is 'I've turned on the fan and the fan has been in operation for 5 hours', can I say this?:
-I have turned on the fan for 5 hours.
///////////////

"Turn on" describes, in this case, an instantaneous action. It is not used for duration. For that use , use 'left on', separable.

I have left the fan on for ... .

Thank you~

Note that 'turn on' can be used in the semi-passive;

I will have the fan turned on for five hours.

meaning "I will arrange to get the fan turned on ...
OR

I will order that the fan be turned on ...

I 'd say:
I turned the fan on 5 hours ago

or

the fan has been on for 5 hours

or

I 've had the fan on for 5 hours now.



I received your letter 5 days ago

or

I 've had your letter for 5 days now

or

I have had possession of your letter for 5 days now.





David

Notice how making this a negative verb changes everything. It is OK to say:

I haven't received your letter for 5 days. (It's been 5 days and I still have not received your letter)

I haven't turned on the fan for 5 hours. (I turned off the fan 5 hours ago and have not turned it on again.)

which is your 1st language? US or UK?

American





David