We were swimming in the lake _______ suddenly it began to rain heavily.
________ we know, the moon goes around the sun.
in the early 20th century, the school keeps on inspiring children’s love of art.
It is one of the funniest things____ on the Internet so far this year.
Though ____ to see the strangers, the housewife gave them a big smile and said hello.
I suppose that there used to be a fairy in the woods, _______?