Matthew's experiment <can't> <may not> <might not> have been bad.

[dewedfrost]

Matthew's experiment was not bad, but he still has to work on it.
Matthew's experiment ______bad, but he still has to work on it.

Hello! I have to complete the sentence to make a deduction in the past using modal verbs like must, may, might, could, may not, might not, can't (+have +past participle).

I've already asked for some advice somewhere else in the Net, but I'd like to ask for your help.

I'd say "Matthew's experiment can't have been bad, but he still has to work on it" (I'm sure the experiment wasn't bad, but Matthew still has to do better).
I'm wondering if "Matthew's experiment may not/might not have been bad,but he still has to work on it" is also possble. (the experiment may have been quite good, but it needs improving).

What would you suggest? Thanks a lot beforehand!

 

[5jj]

If you have to do this, then it is some sort of homework assignment. We don't help with those. Your teacher wants to see what you can do, not what we can do.

 

[dewedfrost]

If you have to do this, then it is some sort of homework assignment. We don't help with those. Your teacher wants to see what you can do, not what we can do.

I see what you mean. As a matter of fact, I'm trying to find the right answer - I've given my opinion , I haven't just asked for your solution, I'm not asking you to do my work, I'm just asking for your suggestion in order to erase any doubts.
I'd be glad to know what you would say in this case. Thanks a lot once again!

 

[emsr2d2]

What answer did you give the person who set you this exercise? Did that person say you were right or wrong?

 

[dewedfrost]

What answer did you give the person who set you this exercise? Did that person say you were right or wrong?

I'm not in a class, I can't ask a teacher! Would you say I'm wrong or right then? Thank you!

 

[emsr2d2]

Let's go back to the start please. You said "I have to complete the sentence ...". Who is forcing you to do this? It's that sentence that led us to believe that this was an exercise set by an English teacher. Remember that if you have copied the question from a text book, you are obliged to provide the title of the book and the name(s) of the author(s).

 

[dewedfrost]

Let's go back to the start please. You said "I have to complete the sentence ...". Who is forcing you to do this? It's that sentence that led us to believe that this was an exercise set by an English teacher. Remember that if you have copied the question from a text book, you are obliged to provide the title of the book and the name(s) of the author(s).

At this very moment, I don't have the book at my disposal, unfortunately. Couldn't you give me your opinion all the same, please?