October 1, 1949 was the day ________ the People’s Republic of China was founded.
Some students use their cellphone ________ as a tool of entertainment.
There in Chongqing ________ great changes in climate this year.
—How much did they ________ for it? —I’m sorry I can’t remember ________, but I bought it at sale.
—Whom did she try to avoid meeting? —________ was a certain boy with the intention of marrying her.
I know the teacher ________ Mary when he spoke of a bright girl.