“Have you seen _____ pen? I left it here this morning.” “Is it _____ black one? I think I saw it somewhere.”
It was _________ to everybody that he was angry.
Whenever I get into trouble, I always _______ Peter.
At minus 130℃, a living cell can be _________ for a thousand year.
Earth is believed ______ by an object the size of Mars at some point in the distant past before itssurface cooled.
our earth, or else it will be no longer fit for us to live on.