'Is until tomorrow' is a fragment, because it has no real subject. You can make it a sentence: What Is until tomorrow?
Fragment.
It is true
A fragment sentence is a partial sentence. It does not have everything it needs to be a full sentence. For example: "The dog" is a fragment.
sentences
You should not capitalize a sentence fragment following a colon.
Fragment
until you eat your vegetables
No, "Unless they answer by tomorrow" is a dependent clause and needs to be paired with an independent clause to form a complete sentence.
Do you work? is a complete sentence; it is not a sentence fragment.
"She wave." is fragment but "She waves" is a sentence.
fragment
It is true
Fragment.
sentence fragment
It is a sentence fragment
is a sentence fragment
Make each fragment into a complete sentence.