—Believe it or not, I have met him before.—No kidding? ________ you've never mentioned it?
—Where did you get this book? —Oh, I ______ it in the bookshop when I was looking for another one.
The plane of the Polish president was about to land ______ it snagged(挂) treetops and crashed, ______ the president and 96 others on board.
Mum ______ to us. “Be quiet! Your little sister is sleeping.”
Einstein’s theory, which was doubted by most scientists at first___out to be correct in the end.
—Thank you for offering me so much advice on English learning, Tom. —_______ .