----Did you open the door? -----Yes. I remembered _____it before you arrived.
A lesson from the terrible drought(干旱) that hit some parts of southwestern China this year is that more anti-drought projects ______ built in the past years.
—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.