—How many people attended the exhibition?—I’m not sure. _____ speaking, a thousand or more.

—How much is _______ for a schoolbag? —Experts say students should carry_______ more than 10 or 15 percent of their body weight.

For our middle school students, some courses are compulsory, while others are ________.

 —Do you still remember the accident ?—Yes. Actually, I have experienced nothing more       .

------ How was your trip to Yungang Caves during your National Day holiday?-------- Wonderfully! I’ve never had _______ one before．