--Look! Someone ______ the laptop.--Well, it wasn’t me. I didn’t do it.
Scientists study ________ human brains work to make computers.
We promise ________ attends the party a chance to have a photo taken with the movie star.
The newcomer went to the library the other day and searched for ________ he could find about Mark Twain.
His writing is so confusing that it's difficult to make out ________ it is he is trying to express.(2011·安徽)
The shocking news made me realize ________ terrible problems we would face.(2011·北京)