She has washed her hair...
Hi everyone!
During my English class, my teacher opposed the following sentences:

(1) She is washing her hair now.
vs.
(2) She has been washing her hair for 10 minutes.

I was wondering if I could use (3) "She has washed her hair for 10 minutes". What do you think of this sentence? Does it seem natural to you?
Would you give me an example where I could use "She has washed..." ?

I thought of:
(4) (?) She has washed her hair with soap for 2 months, in order to save money.
If this one a correct and natural sentence, would it be different in meaning from (5) in any way?

(5) She has been washing her hair with soap for 2 months, in order to save money.

Thanks! :)
[please, correct my English mistakes!]

Question

She has washed her hair...
Hi everyone!
During my English class, my teacher opposed the following sentences:

(1) She is washing her hair now.
vs.
(2) She has been washing her hair for 10 minutes.

I was wondering if I could use (3) "She has washed her hair for 10 minutes". What do you think of this sentence? Does it seem natural to you?
Would you give me an example where I could use "She has washed..." ?

I thought of:
(4) (?) She has washed her hair with soap for 2 months, in order to save money.
If this one a correct and natural sentence, would it be different in meaning from (5) in any way?

(5) She has been washing her hair with soap for 2 months, in order to save money.

Thanks! :)
[please, correct my English mistakes!]

Answer

With this piece of grammar, if you are focusing on the activity (washing hair) or the time period (10 minutes), then you need to use present perfect continuous: "She has been washing her hair for 10 minutes."

If you want to use a simple form of present perfect, then you are focusing on the result. "She has washed her hair" means her hair is clean now. That's all we need to know.

For your last two sentences, the fifth sentence sounds natural.

Answer

(3) doesnt seem natural. its not false, but sounds weird.
ex. she has washed her hair for the interview

(4) means she began washing 2 months ago and stopped after 2 months
(5) means that she began washing 2 months ago and continues to do so.