Unit 10 The Present Perfect or the Past Simple

1 The present perfect can never be used with adverbs which describe finished time periods, such as yesterday, five minutes ago and at three o'clock. If a time adverb is used with the present perfect, it should describe a time period which is unfinished.

Table 5

Time Adverbs
Unfinished Time	Finished Time
today	yesterday
this week	last week
this year	last year
this morning*	this morning*
this afternoon*	this afternoon*
this evening	-
during the last two years	during the summer
since I left school	before I saw you
-	at six o'clock
-	when I met him.
-	five minutes ago
ever	-
just	-

* Can be finished or unfinished, depending on the time of day The teacher hasn't arrived yet. (She might still arrive.) The teacher didn't arrive (The class is over, he can't arrive now) I've spent $20 today. (I can still spend money.) I spent $20 this morning ('this morning' is over, I can't spend any more money 'this morning')

Also use the past simple, even with an adverb of unfinished time, if the action can no longer happen:

I went to the shops today. (But the shops are now closed...)

2 Past simple is used with a definite place for an event because this may suggest a definite time:

I left my bag on the train.

Why didn't you speak to my father yourself on the boat?

Did you see him at the theatre? (= when you were at the theatre? You are not at the theatre now)

I ran into her in Oxford Street. (= when I was in Oxford Street)

Where have you been? - I've been to the opera. - Did you enjoy it? (you are not at the opera now)

3 Similarly, it is the Past Indefinite that is used in questions introduced by when.