[Grammar] I could go with you to the supermarket

[NAL123]

Consider this sentence of mine, please:

I could go with you to the supermarket, but I'm not sure.

Is the above sentence acceptable? ie, can we use could in the above sentence in the sense of possibility or choice (I may go or may not go)?

Could we replace could with might?

 

[emsr2d2]

"I could go to the supermarket with you but I'm not sure" is unusual.

We might say "I could go to the supermarket with you" as an offer to join the other person, perhaps to help with the shopping.
"I'm not sure" would come after saying something you might be able to do but you're not sure if you can.

Helen: I have to go to the supermarket. I've got loads to buy.
Jo: Do you need some help?
Helen: Probably.
Jo: I could go with you.
Helen: That would be great. Thanks.

Helen: I have to go to the supermarket and buy loads of stuff. Can anyone help me?
Jo: I might be able to but I'm not sure. When are you going?
Helen: Later this afternoon.
Jo: That should be OK.