Molly, our bus won't leave until 7:00.
Here's why:
* Comma after "Molly": This is used to separate the name from the rest of the sentence.
* Apostrophe in "won't": This is the contraction for "will not."
* Colon after "until": This is used to introduce the specific time.
* "7:00" needs a colon: The standard way to write time is with a colon separating the hour and minutes.