There was a big forest fire last week, but nobody knows how it .
“Things________never come again!” I couldn’t help talking to myself.
Every one of us must know:________we live can we save the earth.
—Can those________at the back of the classroom hear me?—No problem.
―Why? Where is my cellphone?―Dear me! You _______ it in the taxi!
You need some facts _____ to base your theory.