Making Deductions, Speculation and Certainty

1. Speculating About the Present and Future

Use “might” and “could” to express possibility or uncertainty regarding current or upcoming events. They imply that something is possible but not guaranteed.

Sentence Structures

1. Subject + might/could + base verbExample: She might go to the park later.
2. Subject + might/could not + base verb (negative)Example: He could not attend the meeting.

Dialogue Examples

• Friend: It’s cloudy.
  You: It might rain later this afternoon. 🌧️
• Colleague: John isn’t here yet.
  You: He could be stuck in traffic. 🚗
• Friend: Why isn’t Sarah answering her phone?
  You: She might be busy with something important. 📱
• Friend: My drink tastes strange.
  You: It could have melted ice in it. 🧊
• Colleague: Tom looks pale.
  You: He might feel sick. 🦠
• Friend: I can’t find my cat.
  You: It could be hiding somewhere in the house. 🐱
• Colleague: Did you get an email?
  You: No, but it might come soon. 📧
• Friend: The plane is delayed.
  You: It might be due to weather conditions. ✈️
• Friend: Why is there a camera here?
  You: They could be filming a movie scene. 🎬
• Colleague: Why did our delivery not arrive?
  You: It might have been delayed in transit. 📦

2. Expressing Uncertainty in the Negative

Use “might not” to indicate that something is unlikely or may not happen. This expresses uncertainty in a negative form.

Sentence Structure

Subject + might not + base verb (e.g., He might not join us tonight.)

Dialogue Examples

• Friend: Will Mike join us?
  You: He might not come today; he seemed busy. 📞
• Colleague: Is our boss here already?
  You: No, he might not be in until later. 🏠
• Student: Will the library be open?
  You: It might not open on weekends. 📚
• Friend: Is that John’s car outside?
  You: No, it might not be his; he drives a sedan. 🚙
• Friend: It’s cloudy. Will it rain?
  You: It might not rain though. 🌦️
• Friend: Will there be enough food?
  You: There might not be if many people come. 🍽️
• Colleague: Is your report ready?
  You: I might not finish it today. 🖥️
• Friend: Will your flight be on time?
  You: It might not be due to bad weather. ✈️
• Friend: Will we finish this project by Friday?
  You: We might not meet the deadline. 📅
• Friend: Did you get the invitation?
  You: No, they might not have sent it yet. 📬

3. Deductions and Certainty in the Present with “Must”

Use “must” when you are very certain about something based on evidence or logical reasoning.

Sentence Structure

Subject + must + base verb

Example: He must know the answer.

Dialogue Examples

• Friend: She’s always reading.
  You: She must love books. 📚
• Colleague: It’s 9 a.m., but he’s not here.
  You: He must be running late. 🕰️
• Friend: He’s very fit.
  You: He must work out regularly. 🏋️
• Friend: He drives to work every day.
  You: He must live far from the office. 🏠
• Friend: She’s online all the time.
  You: She must be working remotely. 💻
• Colleague: He’s constantly on the phone.
  You: He must have a lot of clients. 💼
• Friend: He bought a new car.
  You: He must earn a lot. 💵
• Friend: She’s always so positive.
  You: She must enjoy life. 🌞

4. Deductions About the Past

Use “might have,” “could have,” or “must have” to speculate about events that may have occurred in the past.

Sentence Structures

1. Subject + might/could/must have + past participleExample: She must have studied hard.
2. Subject + might not have/could not have + past participleExample: He might not have seen the email.

Dialogue Examples

• Friend: Did you get my message?
  You: I might have missed it—I’ll check again. 📬
• Friend: Why is his car damaged?
  You: He could have had an accident. 🚗
• Colleague: Why wasn’t Sarah at the meeting?
  You: She may have forgotten about it. 📅
• Friend: Why were they late?
  You: They might have missed the bus. 🕰️
• Colleague: Why didn’t the file save?
  You: The system could have crashed. 💻
• Parent: Where’s your backpack?
  You: I may have left it at school. 🎒
• Friend: Why is the soup cold?
  You: Someone might have forgotten to heat it up. 🍲
• Friend: Did I leave my coat here?
  You: You could have left it somewhere else. 🧥
• Friend: Why haven’t we received an update?
  You: They may have delayed it. ✉️
• Colleague: Why did we run out of supplies?
  You: They might have underestimated the demand. 🛒

5. Expressing Impossibility with “Cannot” / “Can’t”

Use “cannot” (or its contraction “can’t”) to express that something is impossible based on evidence or logical reasoning.

Sentence Structure

Subject + cannot/can’t + base verb

Example: That cannot be true.

Dialogue Examples

• Friend: The door opened by itself!
  You: That cannot be possible. Someone must have pushed it.
• Friend: He said he woke up at 3 a.m. and went jogging.
  You: He cannot be serious!
• Friend: The apples turned brown in just a few seconds.
  You: That cannot happen so quickly unless they were already old.
• Friend: The car stopped running because it ran out of gas.
  You: That can’t be true. I just filled the tank this morning!
• Friend: Your dog ate the whole cake.
  You: That cannot be right. He was outside the whole time!
• Friend: She finished all her assignments in an hour.
  You: She can’t have done that! It’s too much work.
• Friend: It’s raining heavily outside.
  You: That cannot be true. The sky is clear!
• Friend: The painting disappeared overnight.
  You: That cannot happen unless someone took it.
• Friend: He says he baked this cake himself.
  You: He cannot have done that. He doesn’t know how to bake!
• Friend: The movie started an hour ago, and they’re already at the ending.
  You: That can’t be right. It’s a two-hour film!