[Grammar] present perfect versus simple past

[hal24]

I am confused about when to use the present perfect versus simple past

Russia has banned gas supply last October.

Russia banned gas supply last October.

 

[Verona_82]

Hi.
Please note I'm not a teacher.

The Present Perfect is not normally used with words that refer to a finished period of time, like yesterday, 5 minutes ago, last month, in 1999, when I was a child etc. This is because the Present Perfect focuses on the present, and words like these focus on the past.

So, in your case, you should use the Past Simple (last October is a reference to the past)

 

[5jj]

Please note I'm not a teacher.

Thank you for reading and following the forum guidelines. I wish others would.

Having said that, I must also say that your advice, when you give it, is usually sound.

You occasionally make mistakes, but readily admit them when they are pointed out. The forum is richer for contributions from members such as you.

Please continue to answer questions - and, of course, to ask them.

 

[MrPedantic]

As a footnote:

The present perfect often expresses a connection or continuum between a past action (or state) and the present.

Thus these two sentences may describe the same event:

1. I have eaten 6 chipolatas.
2. I ate 6 chipolatas.

but in #1, the speaker chooses to express a connection between the event and the time of speaking, whereas in #2 he doesn't.

Hence the unidiomatic nature of a sentence such as:

3. ??? I have eaten 6 chipolates last night.

"I have eaten" maintains the past-present connection; but "last night" places the action firmly in the past and thereby creates an incongruity.

Best wishes,

MrP

 

[mykwyner]

Russia has banned gas supply last October.

If you had said, "Russia has banned [the] gas supply since last October, that would have made the connection to the present and justified the use of the perfect tense.