Have you ever _____ Mudanjiang to see the Jingbo Lake—Yes， I have.

lace is heavily guarded, because inside its walls ________.

that it has been No．1 hit on the pop charts overthe past month·

________students are required to take part in the boat race

Mr. Wu, please _____ how much time you need tofinish your homework.– All right. I’ll make it(做到) at once.