🔁 Grammar: The Present Perfect
1ère Bac Sciences et Technologies Mécaniques STM
📌 Introduction
The Present Perfect connects the past with the present. It’s used for experiences, recent actions, and changes that matter now.
Science Tip: “In lab reports: ‘We have discovered a new bacteria species.'”
🔤 Structure
Affirmative Form
- I/You/We/They have studied → have studied
- He/She/It has studied → has studied
Example: “We have completed the biology project.”
📅 When to Use the Present Perfect
1. Unspecified Past (Experience)
For things that happened at some point in life (no specific time):
“I have studied DNA structure.” (at some point)
2. Recent Actions (with “just”)
For things that happened a short time ago:
“She has just finished her lab report.”
3. Changes Over Time
For changes from past to present:
“Scientists have discovered new planets.”
4. With “ever” and “never”
“Have you ever seen a microscope slide?”
“I have never done a chemistry experiment.”
🕒 Common Time Expressions
With Present Perfect
- already – “We
have already done the test.” - just – “They
have just arrived .” - yet (in questions/negatives) – “Have you finished
yet ?” - ever – “
Have you ever seen a cell under a microscope?” - never – “I
have never used this equipment.” - recently, lately
NOT With Present Perfect
- yesterday
- last week
- in 2020
- on Monday
- two days ago
❌ “I have done the experiment yesterday.” → Use Past Simple
✅ Exercise 1: Choose the Correct Tense
Select Present Perfect or Past Simple:
1. I ___ (finish) my homework.
2. She ___ (do) the experiment yesterday.
3. We ___ (just/complete) the project.
✍️ Exercise 2: Complete the Sentences
Use the Present Perfect:
1. I _______________ (never / see) a real DNA model.
2. Scientists _______________ (discover) many new species.
3. _______________ you _______________ (finish) your report yet?
📌 Summary
- Structure: Subject + have/has + past participle
- Use for: life experiences, recent actions, changes, unfinished time
- Time words: already, just, yet, ever, never, recently
- Not with: yesterday, last week, ago, in 2020
- In science: “We have discovered…”, “Scientists have proven…”
