might have pp vs could have pp

[bosun]

Can I use ' might have pp' instead of ' could have pp' to indicate the same meaning for the following sentence?

My housemate had time to wash the dishes last night, but she went out instead.

_> he/ she could have washed the dishes last night or
->He/she might have washed the dishes last night or
-->He /she may have washed the dishes last night.

 

[5jj]

Can I use ' might have pp' instead of ' could have pp' to indicate the same meaning for the following sentence?

My housemate had time to wash the dishes last night, but she went out instead.

_> he/ she could have washed the dishes last night or
->He/she might have washed the dishes last night or
-->He /she may have washed the dishes last night.

Bosun, please stop asking very similar questions in different threads. You may well find that you receive conflicting answers.

In your sentences above, 'might have' and 'could have' might/could have very similar meanings. Both 'could have washed ...' and 'might have washed ...' could mean 'it is possible that she washed ...' . However, 'could have' could mean 'would have been able to', which 'might have' cannot. We need more context to be absolutely sure.