Can we use "that is" in the following sentence meaning "which means"?
'If I do something, that is when I can do something else...'
I want to show that the underlined section is what the first phrase means.
And, how about the punctuation for 'that is'?
Many thanks in advance.
Should the punctuation always be like the folloeing examples?
---; that is,---
---. That is,---