-- When do you need to pay the balance? -- ______ December 31.
The discovery of new evidence led to________.
—We need to buy some summer clothes, John.—Oh, I never know ________when I'm in the store.
—Isn't Miss Brown here yet?—No.________, she's not here yet.
The temperature is high enough ________water into vapor(蒸汽).
There is no good for the parents to provide everything________their children.