高二英语语法填空和短文改错专项练习语法填空（一）Do you ever wonder why you yawn? Why do you open your mouth wide and take a deep breath? Well, a scientist at the University of Maryland is searching for the answer. Professor Robert Provine has been studying yawning for the past two years. But he says he still does not know 31 people yawn. In fact, no one seems to know much about it. Professor Provine’s students have helped him find out more about yawning. They agreed to 32 (watch) while sitting alone in small rooms. In the rooms, they watched television programs, or pictures of people yawning. Or they just sat and 33 (think) about yawning. Students also kept records of when they yawned throughout the day. The professor says he has learned 34 number of things from these experiments. He says yawning seems linked in some way to sleeping. His students yawned most just before sleeping or 35 waking from sleep. He also found that people yawn much when they are __36 (bore ) or not interested in what they are doing. Now, Professor Provine is planning future experiments to help him find the purpose of yawning. He said there is some evidence 37 yawning is linked to 38 (excite). Yawning is common among runners 39 (wait) to begin a race. It is also common among people waiting to make a speech. Professor Provine says he is most interested in learning why seeing someone yawn makes others yawn as well. He says almost anything connected with yawning can make people yawn. As a matter of fact, I found 40 yawning a lot as I prepared this report. I wonder if hearing it can make you yawn. If it does, excuse me, if you did yawn, write and tell me. （二）Traditional Chinese culture places much e...
