He couldn't have washed his car, it's still dirty.
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Expressing Degrees of Certainty in the Past Tense

1. In American speech Degrees of Certainty means how confident you are about how correct a statement is - you are saying.

2. Degrees of Certainty in the past tense means how confident we are that a specific topic was true or was not true - in the past. This means that the listener is understanding that the action you are discussing, has already happened.



Past Time: Negative
Definition Example
If you are 100% sure about the topic you are discussing, use wasn't or was not. You are 100% sure the topic was not correct.

Was not
, is used for a statement of fact.
(Examples 1, 2, and 3)

1. Tom wasn't sad.

2. Tom wasn't slow, he just won the race.

3. They were not at the theater when we arrived.

If you are 90% sure about the topic you are discussing, use couldn't have been or could not have been. You believe the possibility of the topic being true is very small. (Examples 4 and 5)

4. Seth couldn't have been blind, he just read a magazine.

5. Seth couldn't have been starving, he just ate lunch.

If you are 80% sure about the topic you are discussing, use must not have been. Similar to couldn't have been, you have no evidence to support your opinion. This is a strong belief.

The difference between must not have been and couldn't have been is that you are more sure when using must not have been. (Examples 6 and 7)

6. Sarah wasn't at school yesterday, she must not have been well.

7. Question/Answer:
Question: I thought Tom was injured?

Answer: No, Tom was at soccer practice last week, so he must not have been injured.

If you are 60% sure about the topic you are discussing, use may not have been or might not have been. You are discussing suspicious or uncertain thoughts about the topic.

Question: I don't think Sophia is sick.

Answer: She may not have been.



Past Time: Positive
Definition Example

If you are 100% sure about a topic in the past, use was. You are 100% sure the topic was correct.

Was
, is used for a statement of fact.
(Examples 1 and 2)

1. Tom was happy.

2. Tom was slow, then he practiced, and became fast.

If you are 90% sure about the topic you are discussing, use must have been. You believe the possibility of the topic being true is very small. (Example 3 and 4)

3. Sarah wasn't at school yesterday, she must have been sleeping.

4. The dog must have been hungry, he ate the trash.

If you are 80% sure about the topic you are discussing, use could have been.

The difference between must have been and could have been is that you are more sure when using must have be. (Examples 5 and 6)

5. I don't know if she was sick, she could've been.

6. I don't know if she's still at the party. She could've left early. .

If you are 60% sure about the topic you are discussing, use may have been or might have been.

Remember, even though your thoughts are in the present, the action still happened in the past.
(Examples 7 and 8)

7. Susan went home early. She may have been sick.

8. The dog went through the trash. He might have been hungry.

She was younger than him.
 
 
Exercise
Choose the correct Degree of Certainty for each sentence. Look at the percentage next to the question, then look above to match the Degree of Certainty with the percentage. The first sentence has been completed for you. The exercise will be said in full on the Exercise Answers page. English Logic will put a checkmark ) next to your correct answers.
1.
100%
Terri a girl's name.
2.
90%
My mom a slow driver.
3.
80%
My dad sick.
4.
60%
Your shoes in the closet.
5.
90%
Tom sad.
6.
80%
John on time if he woke up early.
7.
100%
Seth late.
8.
100%
Jake at the store.
9.
90%
Jake at home.
10.
90%
Your keys on the table.


You have right answers out of .

Score: %



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