House prices increased __________ an average of 23% in 1998.A. to B. by C. at
—Can you help me clean the classroom?—___________.
I used to ___________ in the country. But now I am used to ___________ in the city.
He ___________ Taizhou for two weeks.
—How long has Eliza been a nurse?—___________.
—Have you ___________ been to Beijing? —Yes. But only once.