A declarative sentence is a sentence that simply makes a statement. Examples include the two sentences I have just written. Other examples include:
The dog ran.
I will defeat you.
I ate a bagel today.
This type of sentence lives up to its name. It declares something, but does so without showing enthusiasm or asking a question.
It means that whatever remained of your sentence is declared null and void.
For example: The Americans declared independance.
"His nerves are steady as his bat", the sportswriters declared.
That is a declarative sentence, where you have declared (stated) something.
After his conquests,Ying Zheng declared himself emperor of China.
"This lovely gazelle was officially declared extinct in the wild in 1968."
His business went to the dogs and he was declared bankrupt. He was unable to pay his debt and was declared bankrupt. His creditors got nothing as he was declared bankrupt.
Several countries have declared an embargo on purchases of Iranian oil.
Pressing on with declared intention can lead to trouble.
Nablus was declared a closed military zone about an hour ago.
After the storm a state of emergency was declared because of the destruction.
The weatherman was wrong about the weather so often, he was declared aerodynamically misguided.