While talking about past events, many people can be found confused between past and last. Contrary to what many believe, past and last cannot be used interchangeably. They are used to describe different conditions of an event with regards to a particular period or phase of time.
Let’s take a look at the following examples.
I’ve been waiting for you for the last two hours. (incorrect)
I’ve been waiting for you for the past two hours. (correct)
But look at the following examples.
Although he started off really slow, he managed to catch up with the goal in the last three sessions. (not past three sessions)
Although he bowled quite badly in the beginning of the innings, he managed to pick up five wickets in the last two overs. (not past two overs)
Last: We use last when we want to talk about a period of time which is the final phase of a certain activity or event.
Past: We use past when we want to talk about a period of time which has just gone by recently.
So, if you’re talking about waiting for someone (as shown in the examples above), it’s correct to use past two hours since you mean the period (two hours) that has just gone by.
You cannot use last two hours since it’s not a phase of any event. In fact, the only event here is waiting for two hours. In other words, those two hours are the period of time which has just gone by waiting for your friend.
Some more examples…
In his last three years, he wrote two biographies. (described to talk about a person who has passed)
Last Year vs Past Year
Last year means the last calendar year, for example, 2015 (if you’re in 2016).
Past year means the 365 days preceding today. For example, if it was 14th Feb, 2016 today, then the past year would mean the time between 15th Feb, 2015 and 14th Feb, 2016.
He completed his MBA last year (for example 2015) but he’s been looking for a job for the past one year. (for example, from 4th of July, 2015 until 3rd of July, 2016)
Hope this post clarifies your doubts. If you find this post useful, share it with your friends.