Chapter 5-8-3: The Present Perfect / Present Perfect Simple Tense
“I have eaten pasta twice in the last week.”
WHEN TO USE IT: the present perfect tense (also known as the present perfect simple) is used to describe action that began in the past and continues into the present or has just been completed at the moment of utterance. The present perfect is often used to suggest that a past action still has an effect upon something happening in the present.
Use #1: (Unspecified Time Before Now)
to say that an action happened at an unspecified time before now;
the exact time is not important;
the concept of "unspecified time": you CANNOT use the Present Perfect with specific time expressions (yesterday, one year ago, last week, when I was born, when I lived in Montreal, at that moment, on that day, etc.). You CANNOT use the Present Perfect with dependent clauses (also called "subordinate clauses") that are preceded by subordinating conjunctions refer to time (after, as, as long as, as soon as, before, once, 'till, until when). You CAN use the Present Perfect with unspecific expressions such as: ever, never, once, many times, several times, before, so far, already, yet, in the last week, etc. Watch out for this, instructors love to test students' knowledge of this on summative assessments.
Use #2: (Duration from the Past until Now (non-continuous verbs only)
Non-continuous verbs are for things you cannot see somebody doing (to be, to like, to want, to cost, to care, to contain, to owe, to love, to fear, to last, etc.)
Use #2 is similar to the Present Perfect Continuous: we use it to show that something started in the past and has continued up until now
Topics: experience, change over time, accomplishments, an uncompleted action you are expecting, multiple actions at different times
Knowing when a time is specific or unspecific can be difficult. Here are a few examples:
Each of the highlighted compound verbs in the following sentences is in the present perfect tense.
They have not delivered the documents we need.
This sentence suggests that the documents were not delivered in the past and that they are still undelivered.
The health department has decided that all high school students should be immunised against meningitis.
The writer of this sentence uses the present perfect in order to suggest that the decision made in the past is still of importance in the present.
The government has cut university budgets; consequently, the dean has increased the size of most classes.
Here both actions took place sometime in the past and continue to influence the present.
The heat wave has lasted three weeks.
In this sentence, the writer uses the present perfect to indicate that a condition (the heat wave) began in past and continues to affect the present.
Donna has dreamt about frogs sitting in trees every night this week.
Here the action of dreaming has begun in the past and continues into the present.
IMPORTANT NOTE ON THE PRESENT PERFECT:
① REFERENCE TO NON-EXISTENT OBJECTS
The present perfect is only used for subjects that still exist (i.e. it would be a faux pas to talk about someone that has passed away in the present perfect).