—Do you know who the pen________?—Sorry,I don't know.
—Have you ever _____ Mudanjiang to see the Jingbo Lake?—Yes, I have.
You’d better speak aloud ______ we can hear you.
Xiao Li had an accident yesterday _____ he is in No.1 People’s Hospital now.
—Lily, _____ you _____ your ticket?—Not yet!
—What class are you in?—I’m in ____, ____.